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Thakkar N, Abubakar AHA, Shube M, Jama MA, Derow M, Lambach P, Ashmony H, Farid M, Sim SY, O’Connor P, Minta A, Bose AS, Musanhu P, Hasan Q, Bar-Zeev N, Malik SMMR. Estimating the Impact of Vaccination Campaigns on Measles Transmission in Somalia. Vaccines (Basel) 2024; 12:314. [PMID: 38543948 PMCID: PMC10974214 DOI: 10.3390/vaccines12030314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 03/12/2024] [Accepted: 03/13/2024] [Indexed: 04/21/2024] Open
Abstract
Somalia is a complex and fragile setting with a demonstrated potential for disruptive, high-burden measles outbreaks. In response, since 2018, Somalian authorities have partnered with UNICEF and the WHO to implement measles vaccination campaigns across the country. In this paper, we create a Somalia-specific model of measles transmission based on a comprehensive epidemiological dataset including case-based surveillance, vaccine registries, and serological surveys. We use this model to assess the impact of these campaign interventions on Somalian's measles susceptibility, showing, for example, that across the roughly 10 million doses delivered, 1 of every 5 immunized a susceptible child. Finally, we use the model to explore a counter-factual epidemiology without the 2019-2020 campaigns, and we estimate that those interventions prevented over 10,000 deaths.
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Affiliation(s)
- Niket Thakkar
- Institute for Disease Modeling, Bill & Melinda Gates Foundation, Seattle, WA 98109, USA
| | | | - Mukhtar Shube
- Federal Ministry of Health, Mogadishu P.O. Box 22, Somalia
| | | | - Mohamed Derow
- Federal Ministry of Health, Mogadishu P.O. Box 22, Somalia
| | | | | | | | - So Yoon Sim
- World Health Organization, 1202 Geneva, Switzerland
| | | | - Anna Minta
- World Health Organization, 1202 Geneva, Switzerland
| | | | | | - Quamrul Hasan
- World Health Organization, Regional Office for the Eastern Mediterranean, Cairo 11371, Egypt
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Auzenbergs M, Fu H, Abbas K, Procter SR, Cutts FT, Jit M. Health effects of routine measles vaccination and supplementary immunisation activities in 14 high-burden countries: a Dynamic Measles Immunization Calculation Engine (DynaMICE) modelling study. Lancet Glob Health 2023; 11:e1194-e1204. [PMID: 37474227 PMCID: PMC10369016 DOI: 10.1016/s2214-109x(23)00220-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 04/17/2023] [Accepted: 05/02/2023] [Indexed: 07/22/2023]
Abstract
BACKGROUND WHO recommends at least 95% population coverage with two doses of measles-containing vaccine (MCV). Most countries worldwide use routine services to offer a first dose of measles-containing vaccine (MCV1) and later, a second dose of measles-containing vaccine (MCV2). Many countries worldwide conduct supplementary immunisation activities (SIAs), offering vaccination to all people in a specific age range irrespective of previous vaccination history. We aimed to estimate the relative effects of each dose and delivery route in 14 countries with high measles burden. METHODS We used an age-structured compartmental dynamic model, the Dynamic Measles Immunization Calculation Engine (DynaMICE), to assess the effects of different vaccination strategies on measles susceptibility and burden during 2000-20 in 14 countries with high measles incidence (containing 53% of the global birth cohort and 78% of the global measles burden). Country-specific routine MCV1 and MCV2 coverage data during 1980-2020 were obtained from the WHO and UNICEF Estimates of National Immunization Coverage database for all modelled countries and SIA data were obtained from the WHO summary of measles and rubella SIAs. We estimated the incremental health effects of different vaccination strategies using prevented cases of measles and deaths from measles and their efficiency using the incremental number needed to vaccinate (NNV) to prevent an additional measles case. FINDINGS Compared with no vaccination, MCV1 implementation was estimated to have prevented 824 million cases of measles and 9·6 million deaths from measles, with a median NNV of 1·41 (IQR 1·35-1·44). Adding routine MCV2 to MCV1 was estimated to have prevented 108 million cases and 404 270 deaths, whereas adding SIAs to MCV1 was estimated to have prevented 256 million cases and 4·4 million deaths. Despite larger incremental effects, adding SIAs to MCV1 (median incremental NNV 6·02, 5·30-7·68) showed reduced efficiency compared with adding routine MCV2 (5·41, 4·76-6·11). INTERPRETATION Vaccination strategies, including non-selective SIAs, reach a greater proportion of children who are unvaccinated and reduce measles burden more than MCV2 alone, but efficiency is lower because of the wide age range targeted by SIAs. This analysis provides information to help improve the health effects and efficiency of measles vaccination strategies. The interplay between MCV1, MCV2, and SIAs should be considered when planning future measles vaccination strategies. FUNDING Gavi, the Vaccine Alliance and the Bill & Melinda Gates Foundation.
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Affiliation(s)
- Megan Auzenbergs
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.
| | - Han Fu
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Kaja Abbas
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK; Public Health Foundation of India, New Delhi, India
| | - Simon R Procter
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Felicity T Cutts
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Mark Jit
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK; School of Public Health, University of Hong Kong, Hong Kong Special Administrative Region, China
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3
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Phillips MT, Antillon M, Bilcke J, Bar-Zeev N, Limani F, Debellut F, Pecenka C, Neuzil KM, Gordon MA, Thindwa D, Paltiel AD, Yaesoubi R, Pitzer VE. Cost-effectiveness analysis of typhoid conjugate vaccines in an outbreak setting: a modeling study. BMC Infect Dis 2023; 23:143. [PMID: 36890448 PMCID: PMC9993384 DOI: 10.1186/s12879-023-08105-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 02/20/2023] [Indexed: 03/10/2023] Open
Abstract
BACKGROUND Several prolonged typhoid fever epidemics have been reported since 2010 throughout eastern and southern Africa, including Malawi, caused by multidrug-resistant Salmonella Typhi. The World Health Organization recommends the use of typhoid conjugate vaccines (TCVs) in outbreak settings; however, current data are limited on how and when TCVs might be introduced in response to outbreaks. METHODOLOGY We developed a stochastic model of typhoid transmission fitted to data from Queen Elizabeth Central Hospital in Blantyre, Malawi from January 1996 to February 2015. We used the model to evaluate the cost-effectiveness of vaccination strategies over a 10-year time horizon in three scenarios: (1) when an outbreak is likely to occur; (2) when an outbreak is unlikely to occur within the next ten years; and (3) when an outbreak has already occurred and is unlikely to occur again. We considered three vaccination strategies compared to the status quo of no vaccination: (a) preventative routine vaccination at 9 months of age; (b) preventative routine vaccination plus a catch-up campaign to 15 years of age; and (c) reactive vaccination with a catch-up campaign to age 15 (for Scenario 1). We also explored variations in outbreak definitions, delays in implementation of reactive vaccination, and the timing of preventive vaccination relative to the outbreak. RESULTS Assuming an outbreak occurs within 10 years, we estimated that the various vaccination strategies would prevent a median of 15-60% of disability-adjusted life-years (DALYs). Reactive vaccination was the preferred strategy for WTP values of $0-300 per DALY averted. For WTP values > $300, introduction of preventative routine TCV immunization with a catch-up campaign was the preferred strategy. Routine vaccination with a catch-up campaign was cost-effective for WTP values above $890 per DALY averted if no outbreak occurs and > $140 per DALY averted if implemented after the outbreak has already occurred. CONCLUSIONS Countries for which the spread of antimicrobial resistance is likely to lead to outbreaks of typhoid fever should consider TCV introduction. Reactive vaccination can be a cost-effective strategy, but only if delays in vaccine deployment are minimal; otherwise, introduction of preventive routine immunization with a catch-up campaign is the preferred strategy.
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Affiliation(s)
- Maile T Phillips
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College St., P.O. Box 208034, New Haven, CT, 06520-8034, USA
| | - Marina Antillon
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Joke Bilcke
- Center for Health Economics Research and Modeling Infectious Diseases, University of Antwerp, Antwerp, Belgium
| | - Naor Bar-Zeev
- International Vaccine Access Center, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Malawi Liverpool Wellcome Programme, Blantyre, Malawi
| | - Fumbani Limani
- Malawi Liverpool Wellcome Programme, Blantyre, Malawi.,Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Clint Pecenka
- Center for Vaccine Innovation and Access, PATH, Seattle, WA, USA
| | - Kathleen M Neuzil
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Melita A Gordon
- Malawi Liverpool Wellcome Programme, Blantyre, Malawi.,Kamuzu University of Health Sciences, Blantyre, Malawi.,Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Deus Thindwa
- Malawi Liverpool Wellcome Programme, Blantyre, Malawi.,Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - A David Paltiel
- Department of Health Policy, Yale School of Public Health, New Haven, CT, USA
| | - Reza Yaesoubi
- Department of Health Policy, Yale School of Public Health, New Haven, CT, USA
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College St., P.O. Box 208034, New Haven, CT, 06520-8034, USA.
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Butzin-Dozier Z, Athni TS, Benjamin-Chung J. A Review of the Ring Trial Design for Evaluating Ring Interventions for Infectious Diseases. Epidemiol Rev 2022; 44:29-54. [PMID: 35593400 PMCID: PMC10362935 DOI: 10.1093/epirev/mxac003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 03/25/2022] [Accepted: 05/12/2022] [Indexed: 12/29/2022] Open
Abstract
In trials of infectious disease interventions, rare outcomes and unpredictable spatiotemporal variation can introduce bias, reduce statistical power, and prevent conclusive inferences. Spillover effects can complicate inference if individual randomization is used to gain efficiency. Ring trials are a type of cluster-randomized trial that may increase efficiency and minimize bias, particularly in emergency and elimination settings with strong clustering of infection. They can be used to evaluate ring interventions, which are delivered to individuals in proximity to or contact with index cases. We conducted a systematic review of ring trials, compare them with other trial designs for evaluating ring interventions, and describe strengths and weaknesses of each design. Of 849 articles and 322 protocols screened, we identified 26 ring trials, 15 cluster-randomized trials, 5 trials that randomized households or individuals within rings, and 1 individually randomized trial. The most common interventions were postexposure prophylaxis (n = 23) and focal mass drug administration and screening and treatment (n = 7). Ring trials require robust surveillance systems and contact tracing for directly transmitted diseases. For rare diseases with strong spatiotemporal clustering, they may have higher efficiency and internal validity than cluster-randomized designs, in part because they ensure that no clusters are excluded from analysis due to zero cluster incidence. Though more research is needed to compare them with other types of trials, ring trials hold promise as a design that can increase trial speed and efficiency while reducing bias.
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Zhou W, Zhang F, Cui S, Chang KC. Is There Always a Negative Causality between Human Health and Environmental Degradation? Current Evidence from Rural China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:10561. [PMID: 36078273 PMCID: PMC9517924 DOI: 10.3390/ijerph191710561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/21/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
This study explores the incidence and trend of zoonoses in China and its relationship with environmental health and proposes suggestions for promoting the long-term sustainable development of human, animal, and environmental systems. The incidence of malaria was selected as the dependent variable, and the consumption of agricultural diesel oil and pesticides and investment in lavatory sanitation improvement in rural areas were selected as independent variables according to the characteristics of nonpoint source pollution and domestic pollution in China's rural areas. By employing a fixed effects regression model, the results indicated that the use of pesticides was negatively associated with the incidence of malaria, continuous investment in rural toilet improvement, and an increase in economic income can play a positive role in the prevention and control of malaria incidence. Guided by the theory of One Health, this study verifies human, animal, and environmental health as a combination of mutual restriction and influence, discusses the complex causal relationship among the three, and provides evidence for sustainable development and integrated governance.
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Affiliation(s)
- Wei Zhou
- College of Public Administration and Law, Hunan Agricultural University, Changsha 410128, China
| | - Fan Zhang
- College of Public Administration and Law, Hunan Agricultural University, Changsha 410128, China
| | - Shihao Cui
- College of Public Administration and Law, Hunan Agricultural University, Changsha 410128, China
| | - Ke-Chiun Chang
- School of Economics and Management, Wuhan University, Wuhan 430072, China
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Tredennick AT, O'Dea EB, Ferrari MJ, Park AW, Rohani P, Drake JM. Anticipating infectious disease re-emergence and elimination: a test of early warning signals using empirically based models. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220123. [PMID: 35919978 PMCID: PMC9346357 DOI: 10.1098/rsif.2022.0123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Timely forecasts of the emergence, re-emergence and elimination of human infectious diseases allow for proactive, rather than reactive, decisions that save lives. Recent theory suggests that a generic feature of dynamical systems approaching a tipping point-early warning signals (EWS) due to critical slowing down (CSD)-can anticipate disease emergence and elimination. Empirical studies documenting CSD in observed disease dynamics are scarce, but such demonstration of concept is essential to the further development of model-independent outbreak detection systems. Here, we use fitted, mechanistic models of measles transmission in four cities in Niger to detect CSD through statistical EWS. We find that several EWS accurately anticipate measles re-emergence and elimination, suggesting that CSD should be detectable before disease transmission systems cross key tipping points. These findings support the idea that statistical signals based on CSD, coupled with decision-support algorithms and expert judgement, could provide the basis for early warning systems of disease outbreaks.
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Affiliation(s)
- Andrew T Tredennick
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.,Western EcoSystems Technology, Inc., 1610 East Reynolds Street, Laramie, WY 82070, USA
| | - Eamon B O'Dea
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - Matthew J Ferrari
- The Center for Infectious Disease Dynamics and Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Andrew W Park
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.,Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - Pejman Rohani
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.,Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - John M Drake
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
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7
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Lerch A, Ten Bosch QA, L'Azou Jackson M, Bettis AA, Bernuzzi M, Murphy GAV, Tran QM, Huber JH, Siraj AS, Bron GM, Elliott M, Hartlage CS, Koh S, Strimbu K, Walters M, Perkins TA, Moore SM. Projecting vaccine demand and impact for emerging zoonotic pathogens. BMC Med 2022; 20:202. [PMID: 35705986 PMCID: PMC9200440 DOI: 10.1186/s12916-022-02405-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 05/14/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Despite large outbreaks in humans seeming improbable for a number of zoonotic pathogens, several pose a concern due to their epidemiological characteristics and evolutionary potential. To enable effective responses to these pathogens in the event that they undergo future emergence, the Coalition for Epidemic Preparedness Innovations is advancing the development of vaccines for several pathogens prioritized by the World Health Organization. A major challenge in this pursuit is anticipating demand for a vaccine stockpile to support outbreak response. METHODS We developed a modeling framework for outbreak response for emerging zoonoses under three reactive vaccination strategies to assess sustainable vaccine manufacturing needs, vaccine stockpile requirements, and the potential impact of the outbreak response. This framework incorporates geographically variable zoonotic spillover rates, human-to-human transmission, and the implementation of reactive vaccination campaigns in response to disease outbreaks. As proof of concept, we applied the framework to four priority pathogens: Lassa virus, Nipah virus, MERS coronavirus, and Rift Valley virus. RESULTS Annual vaccine regimen requirements for a population-wide strategy ranged from > 670,000 (95% prediction interval 0-3,630,000) regimens for Lassa virus to 1,190,000 (95% PrI 0-8,480,000) regimens for Rift Valley fever virus, while the regimens required for ring vaccination or targeting healthcare workers (HCWs) were several orders of magnitude lower (between 1/25 and 1/700) than those required by a population-wide strategy. For each pathogen and vaccination strategy, reactive vaccination typically prevented fewer than 10% of cases, because of their presently low R0 values. Targeting HCWs had a higher per-regimen impact than population-wide vaccination. CONCLUSIONS Our framework provides a flexible methodology for estimating vaccine stockpile needs and the geographic distribution of demand under a range of outbreak response scenarios. Uncertainties in our model estimates highlight several knowledge gaps that need to be addressed to target vulnerable populations more accurately. These include surveillance gaps that mask the true geographic distribution of each pathogen, details of key routes of spillover from animal reservoirs to humans, and the role of human-to-human transmission outside of healthcare settings. In addition, our estimates are based on the current epidemiology of each pathogen, but pathogen evolution could alter vaccine stockpile requirements.
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Affiliation(s)
- Anita Lerch
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Quirine A Ten Bosch
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, The Netherlands
| | | | - Alison A Bettis
- Coalition for Epidemic Preparedness Innovations (CEPI), Oslo, Norway
| | - Mauro Bernuzzi
- Coalition for Epidemic Preparedness Innovations (CEPI), London, UK
| | | | - Quan M Tran
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - John H Huber
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Amir S Siraj
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Gebbiena M Bron
- Quantitative Veterinary Epidemiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Margaret Elliott
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Carson S Hartlage
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Sojung Koh
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Kathyrn Strimbu
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Magdalene Walters
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - T Alex Perkins
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
| | - Sean M Moore
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
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8
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Agent-based modelling of reactive vaccination of workplaces and schools against COVID-19. Nat Commun 2022; 13:1414. [PMID: 35301289 PMCID: PMC8931017 DOI: 10.1038/s41467-022-29015-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 02/17/2022] [Indexed: 12/30/2022] Open
Abstract
With vaccination against COVID-19 stalled in some countries, increasing vaccine accessibility and distribution could help keep transmission under control. Here, we study the impact of reactive vaccination targeting schools and workplaces where cases are detected, with an agent-based model accounting for COVID-19 natural history, vaccine characteristics, demographics, behavioural changes and social distancing. In most scenarios, reactive vaccination leads to a higher reduction in cases compared with non-reactive strategies using the same number of doses. The reactive strategy could however be less effective than a moderate/high pace mass vaccination program if initial vaccination coverage is high or disease incidence is low, because few people would be vaccinated around each case. In case of flare-ups, reactive vaccination could better mitigate spread if it is implemented quickly, is supported by enhanced test-trace-isolate and triggers an increased vaccine uptake. These results provide key information to plan an adaptive vaccination rollout. The authors use an agent-based model to investigate the potential of reactive vaccination strategies for COVID-19 outbreak mitigation. They find that distributing vaccines in schools and workplaces where cases are detected is more impactful than non-reactive strategies in a wide range of epidemic scenarios.
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9
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Azam JM, Saitta B, Bonner K, Ferrari MJ, Pulliam JRC. Modelling the relative benefits of using the measles vaccine outside cold chain for outbreak response. Vaccine 2021; 39:5845-5853. [PMID: 34481696 DOI: 10.1016/j.vaccine.2021.08.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/30/2021] [Accepted: 08/13/2021] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Rapid outbreak response vaccination is a strategy for measles control and elimination. Measles vaccines must be stored and transported within a specified temperature range, but this can present significant challenges when targeting remote populations. Measles vaccine licensure for delivery outside cold chain (OCC) could provide more vaccine transport/storage space without ice packs, and a solution to shorten response times. However, due to vaccine safety and wastage considerations, the OCC strategy will require other operational changes, potentially including the use of 1-dose (monodose) instead of 10-dose vials, requiring larger transport/storage equipment currently achieved with 10-dose vials. These trade-offs require quantitative comparisons of vaccine delivery options to evaluate their relative benefits. METHODS We developed a modelling framework combining elements of the vaccine supply chain - cold chain, vial, team, and transport equipment types - with a measles transmission dynamics model to compare vaccine delivery options. We compared 10 strategies resulting from combinations of the vaccine supply elements and grouped into three main classes: OCC, partial cold chain (PCC), and full cold chain (FCC). For each strategy, we explored a campaign with 20 teams sequentially targeting 5 locations with 100,000 individuals each. We characterised the time needed to freeze ice packs and complete the campaign (campaign duration), vaccination coverage, and cases averted, assuming a fixed pre-deployment delay before campaign commencement. We performed sensitivity analyses of the pre-deployment delay, population sizes, and two team allocation schemes. RESULTS The OCC, PCC, and FCC strategies achieve campaign durations of 50, 51, and 52 days, respectively. Nine of the ten strategies can achieve a vaccination coverage of 80%, and OCC averts the most cases. DISCUSSION The OCC strategy, therefore, presents improved operational and epidemiological outcomes relative to current practice and the other options considered.
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Affiliation(s)
- James M Azam
- DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa.
| | - Barbara Saitta
- Access Campaign, Médecins Sans Frontières, New York, United States
| | - Kimberly Bonner
- University of Minnesota, Twin Cities, Minneapolis, United States
| | - Matthew J Ferrari
- The Center for Infectious Disease Dynamics, The Pennsylvania State University, PA, United States
| | - Juliet R C Pulliam
- DSI-NRF Centre of Excellence in Epidemiological Modelling and Analysis, Stellenbosch University, Stellenbosch, South Africa
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Decouttere C, De Boeck K, Vandaele N. Advancing sustainable development goals through immunization: a literature review. Global Health 2021; 17:95. [PMID: 34446050 PMCID: PMC8390056 DOI: 10.1186/s12992-021-00745-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 07/23/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Immunization directly impacts health (SDG3) and brings a contribution to 14 out of the 17 Sustainable Development Goals (SDGs), such as ending poverty, reducing hunger, and reducing inequalities. Therefore, immunization is recognized to play a central role in reaching the SDGs, especially in low- and middle-income countries (LMICs). Despite continuous interventions to strengthen immunization systems and to adequately respond to emergency immunization during epidemics, the immunization-related indicators for SDG3 lag behind in sub-Saharan Africa. Especially taking into account the current Covid19 pandemic, the current performance on the connected SDGs is both a cause and a result of this. METHODS We conduct a literature review through a keyword search strategy complemented with handpicking and snowballing from earlier reviews. After title and abstract screening, we conducted a qualitative analysis of key insights and categorized them according to showing the impact of immunization on SDGs, sustainability challenges, and model-based solutions to these challenges. RESULTS We reveal the leveraging mechanisms triggered by immunization and position them vis-à-vis the SDGs, within the framework of Public Health and Planetary Health. Several challenges for sustainable control of vaccine-preventable diseases are identified: access to immunization services, global vaccine availability to LMICs, context-dependent vaccine effectiveness, safe and affordable vaccines, local/regional vaccine production, public-private partnerships, and immunization capacity/capability building. Model-based approaches that support SDG-promoting interventions concerning immunization systems are analyzed in light of the strategic priorities of the Immunization Agenda 2030. CONCLUSIONS In general terms, it can be concluded that relevant future research requires (i) design for system resilience, (ii) transdisciplinary modeling, (iii) connecting interventions in immunization with SDG outcomes, (iv) designing interventions and their implementation simultaneously, (v) offering tailored solutions, and (vi) model coordination and integration of services and partnerships. The research and health community is called upon to join forces to activate existing knowledge, generate new insights and develop decision-supporting tools for Low-and Middle-Income Countries' health authorities and communities to leverage immunization in its transformational role toward successfully meeting the SDGs in 2030.
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Affiliation(s)
- Catherine Decouttere
- KU Leuven, Access-To-Medicines research Center, Naamsestraat 69, Leuven, Belgium
| | - Kim De Boeck
- KU Leuven, Access-To-Medicines research Center, Naamsestraat 69, Leuven, Belgium
| | - Nico Vandaele
- KU Leuven, Access-To-Medicines research Center, Naamsestraat 69, Leuven, Belgium
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11
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Raherindrasana A, Metcalf CJ, Heraud JM, Cauchemez S, Winter A, Wesolowski A, Razafindratsimandresy R, Randriamampionona L, Rafalimanantsoa SA, Masembe Y, Ndiaye C, Rakotonirina J. Towards better targeting: lessons from a posthoneymoon measles outbreak in Madagascar, 2018-2019. BMJ Glob Health 2021; 5:bmjgh-2020-003153. [PMID: 33082133 PMCID: PMC7577030 DOI: 10.1136/bmjgh-2020-003153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 09/01/2020] [Accepted: 09/02/2020] [Indexed: 11/16/2022] Open
Affiliation(s)
- Antso Raherindrasana
- Ministry of Public Health, Antananarivo, Madagascar.,Faculty of Medicine of Antananarivo, University of Antananarivo, Antananarivo, Madagascar
| | - C Jessica Metcalf
- Dept of Ecology and Evol. Biology, Princeton University, Princeton, New Jersey, USA .,Princeton School of Public and International Affairs, Princeton University, Princeton, New Jersey, USA
| | | | - Simon Cauchemez
- Mathematical Modelling of Infectious Diseases Unit, Institut Pasteur, Paris, France
| | - Amy Winter
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Amy Wesolowski
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | | | | | | | - Yolande Masembe
- Madagascar Office, World Health Organization, Antananarivo, Madagascar
| | - Charlotte Ndiaye
- Madagascar Office, World Health Organization, Antananarivo, Madagascar
| | - Julio Rakotonirina
- Ministry of Public Health, Antananarivo, Madagascar.,Faculty of Medicine of Antananarivo, University of Antananarivo, Antananarivo, Madagascar
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12
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Li R, Bjørnstad ON, Stenseth NC. Switching vaccination among target groups to achieve improved long-lasting benefits. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210292. [PMID: 34150317 PMCID: PMC8206705 DOI: 10.1098/rsos.210292] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 06/04/2021] [Indexed: 05/15/2023]
Abstract
The development of vaccines has opened a way to lower the public health and societal burden of COVID-19 pandemic. To achieve sustainable gains in the long term, switching the vaccination from one target group to a more diverse portfolio should be planned appropriately. We lay out a general mathematical framework for comparing alternative vaccination roll-out strategies for the year to come: single focus groups: (i-a) the high-risk older age groups and (i-b) the core-sociable groups; and two focus groups: (ii-a) mixed vaccination of both the high-risk and core-sociable groups simultaneously and (ii-b) cyclic vaccination switching between groups. Featuring analyses of all relevant data including age pyramids for 15 representative countries with diverse social mixing patterns shows that mixed strategies that result in both direct and indirect protection of high-risk groups may be better for the overall societal health impact of COVID-19 vaccine roll-out. Of note, over time switching the priority from high-risk older age groups to core-sociable groups responsible for heightened circulation and thus indirect risk may be increasingly advantageous.
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Affiliation(s)
- Ruiyun Li
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Ottar N. Bjørnstad
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, 0316 Oslo, Norway
- Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
| | - Nils Chr. Stenseth
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, 0316 Oslo, Norway
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13
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Matter D, Potgieter L. Allocating epidemic response teams and vaccine deliveries by drone in generic network structures, according to expected prevented exposures. PLoS One 2021; 16:e0248053. [PMID: 33667263 PMCID: PMC7935281 DOI: 10.1371/journal.pone.0248053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 02/18/2021] [Indexed: 11/19/2022] Open
Abstract
The tumultuous inception of an epidemic is usually accompanied by difficulty in determining how to respond best. In developing nations, this can be compounded by logistical challenges, such as vaccine shortages and poor road infrastructure. To provide guidance towards improved epidemic response, various resource allocation models, in conjunction with a network-based SEIRVD epidemic model, are proposed in this article. Further, the feasibility of using drones for vaccine delivery is evaluated, and assorted relevant parameters are discussed. For the sake of generality, these results are presented for multiple network structures, representing interconnected populations-upon which repeated epidemic simulations are performed. The resource allocation models formulated maximise expected prevented exposures on each day of a simulated epidemic, by allocating response teams and vaccine deliveries according to the solutions of two respective integer programming problems-thereby influencing the simulated epidemic through the SEIRVD model. These models, when compared with a range of alternative resource allocation strategies, were found to reduce both the number of cases per epidemic, and the number of vaccines required. Consequently, the recommendation is made that such models be used as decision support tools in epidemic response. In the absence thereof, prioritizing locations for vaccinations according to susceptible population, rather than total population or number of infections, is most effective for the majority of network types. In other results, fixed-wing drones are demonstrated to be a viable delivery method for vaccines in the context of an epidemic, if sufficient drones can be promptly procured; the detrimental effect of intervention delay was discovered to be significant. In addition, the importance of well-documented routine vaccination activities is highlighted, due to the benefits of increased pre-epidemic immunity rates, and targeted vaccination.
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Affiliation(s)
- Dean Matter
- Department of Logistics, Stellenbosch University, Stellenbosch, Western Cape, South Africa
| | - Linke Potgieter
- Department of Logistics, Stellenbosch University, Stellenbosch, Western Cape, South Africa
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14
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Knight GM, Glover RE, McQuaid CF, Olaru ID, Gallandat K, Leclerc QJ, Fuller NM, Willcocks SJ, Hasan R, van Kleef E, Chandler CIR. Antimicrobial resistance and COVID-19: Intersections and implications. eLife 2021; 10:e64139. [PMID: 33588991 PMCID: PMC7886324 DOI: 10.7554/elife.64139] [Citation(s) in RCA: 150] [Impact Index Per Article: 50.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/02/2021] [Indexed: 01/08/2023] Open
Abstract
Before the coronavirus 2019 (COVID-19) pandemic began, antimicrobial resistance (AMR) was among the top priorities for global public health. Already a complex challenge, AMR now needs to be addressed in a changing healthcare landscape. Here, we analyse how changes due to COVID-19 in terms of antimicrobial usage, infection prevention, and health systems affect the emergence, transmission, and burden of AMR. Increased hand hygiene, decreased international travel, and decreased elective hospital procedures may reduce AMR pathogen selection and spread in the short term. However, the opposite effects may be seen if antibiotics are more widely used as standard healthcare pathways break down. Over 6 months into the COVID-19 pandemic, the dynamics of AMR remain uncertain. We call for the AMR community to keep a global perspective while designing finely tuned surveillance and research to continue to improve our preparedness and response to these intersecting public health challenges.
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Affiliation(s)
- Gwenan M Knight
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Centre for Mathematical Modelling of Infectious Diseases (CMMID), LSHTMLondonUnited Kingdom
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Public Health, LSHTMLondonUnited Kingdom
- TB Centre, LSHTMLondonUnited Kingdom
| | - Rebecca E Glover
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Department of Health Services Research and Policy, Faculty of Public Health and Policy, LSHTMLondonUnited Kingdom
| | - C Finn McQuaid
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Centre for Mathematical Modelling of Infectious Diseases (CMMID), LSHTMLondonUnited Kingdom
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Public Health, LSHTMLondonUnited Kingdom
- TB Centre, LSHTMLondonUnited Kingdom
| | - Ioana D Olaru
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, LSHTMLondonUnited Kingdom
- Biomedical Research and Training InstituteZambezi RiverZimbabwe
| | - Karin Gallandat
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, LSHTMLondonUnited Kingdom
| | - Quentin J Leclerc
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Centre for Mathematical Modelling of Infectious Diseases (CMMID), LSHTMLondonUnited Kingdom
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Public Health, LSHTMLondonUnited Kingdom
| | - Naomi M Fuller
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Centre for Mathematical Modelling of Infectious Diseases (CMMID), LSHTMLondonUnited Kingdom
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Public Health, LSHTMLondonUnited Kingdom
| | - Sam J Willcocks
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, LSHTMLondonUnited Kingdom
| | - Rumina Hasan
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Department of Pathology and Laboratory Medicine, Aga Khan UniversityKarachiPakistan
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, LSHTMLondonUnited Kingdom
| | - Esther van Kleef
- Department of Public Heath, Institute of Tropical MedicineAntwerpBelgium
| | - Clare IR Chandler
- AMR Centre, London School of Hygiene and Tropical Medicine (LSHTM)LondonUnited Kingdom
- Department of Global Health and Development, Faculty of Public Health and Policy, LSHTMLondonUnited Kingdom
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15
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Mathematical Model of the Role of Asymptomatic Infection in Outbreaks of Some Emerging Pathogens. Trop Med Infect Dis 2020; 5:tropicalmed5040184. [PMID: 33317176 PMCID: PMC7768460 DOI: 10.3390/tropicalmed5040184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/19/2020] [Accepted: 12/01/2020] [Indexed: 01/15/2023] Open
Abstract
Preparation for outbreaks of emerging infectious diseases is often predicated on beliefs that we will be able to understand the epidemiological nature of an outbreak early into its inception. However, since many rare emerging diseases exhibit different epidemiological behaviors from outbreak to outbreak, early and accurate estimation of the epidemiological situation may not be straightforward in all cases. Previous studies have proposed considering the role of active asymptomatic infections co-emerging and co-circulating as part of the process of emergence of a novel pathogen. Thus far, consideration of the role of asymptomatic infections in emerging disease dynamics have usually avoided considering some important sets of influences. In this paper, we present and analyze a mathematical model to explore the hypothetical scenario that some (re)emerging diseases may actually be able to maintain stable, endemic circulation successfully in an entirely asymptomatic state. We argue that an understanding of this potential mechanism for diversity in observed epidemiological dynamics may be of considerable importance in understanding and preparing for outbreaks of novel and/or emerging diseases.
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16
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Wongsanuphat S, Thitichai P, Jaiyong R, Plernprom P, Thintip K, Jitpeera C, Suphanchaimat R. Investigation of Measles Outbreak among Thai and Migrant Workers in Two Factories in Nakhon Pathom, Thailand, 2019. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17134627. [PMID: 32605070 PMCID: PMC7369850 DOI: 10.3390/ijerph17134627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/12/2020] [Accepted: 06/22/2020] [Indexed: 11/24/2022]
Abstract
On 22 March 2019 the Thai Department of Disease Control (DDC) was notified that 16 workers, including Thai and Myanmar migrant workers, from two factories located in Nakhon Phathom Province, had presented with a fever with rash during the previous 2 weeks. Active case finding was conducted among workers in both factories using face-to-face interviews. Suspected cases were defined as a worker who developed fever with rash with one of the following symptoms: cough, coryza or conjunctivitis. Testing for measles IgM antibodies and viral identification through throat swabs by polymerase chain reaction (PCR) were performed to confirm diagnosis. Vaccination history among cases was reviewed. Nationality and age-specific attack rates (AR) were calculated. An environmental study and a social network analysis were conducted to better understand the transmission process. A total 56 cases (AR = 0.97%) were identified. Of 21 serum measles IgM collected, 8 (38.0%) were positive. Of 8 throat swabs collected, 5 (62.5%) were positive for measles genotype D8. The disease attack rate in migrant employees was twice as large as the rate in Thai counterparts (AR = 0.7 and 1.4%). The first case was identified as a Myanmar worker who arrived in Thailand two weeks prior to his illness. The Myanmar workers’ accommodation was more crowded than that for Thai workers. The hot spots of transmission were found at a drinking water tank which had shared glasses. Among the cases, 62.5% could not recall their vaccination history, and 25% had never had an injection containing a measles vaccination. The majority of migrant cases had never completed a two-dose measles vaccination. To halt the outbreak, measles vaccines were administered to the employees, particularly those working in the same sections with the cases and shared glasses were removed. For future policy action, a vaccination program should be incorporated into the work permit issuance process.
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Affiliation(s)
- Suphanat Wongsanuphat
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
| | - Phanthanee Thitichai
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
| | - Rungrot Jaiyong
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
| | - Patchanee Plernprom
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
| | - Kanthika Thintip
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
| | - Charuttaporn Jitpeera
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
| | - Rapeepong Suphanchaimat
- Division of Epidemiology, Department of Disease Control, Ministry of Public Health and Thailand, Nonthaburi 11000, Thailand; (S.W.); (P.T.); (R.J.); (P.P.); (K.T.); (C.J.)
- International Health Policy Program, Ministry of Public Health, Nonthaburi 11000, Thailand
- Correspondence:
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17
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Polonsky JA, Baidjoe A, Kamvar ZN, Cori A, Durski K, Edmunds WJ, Eggo RM, Funk S, Kaiser L, Keating P, de Waroux OLP, Marks M, Moraga P, Morgan O, Nouvellet P, Ratnayake R, Roberts CH, Whitworth J, Jombart T. Outbreak analytics: a developing data science for informing the response to emerging pathogens. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180276. [PMID: 31104603 PMCID: PMC6558557 DOI: 10.1098/rstb.2018.0276] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Despite continued efforts to improve health systems worldwide, emerging pathogen epidemics remain a major public health concern. Effective response to such outbreaks relies on timely intervention, ideally informed by all available sources of data. The collection, visualization and analysis of outbreak data are becoming increasingly complex, owing to the diversity in types of data, questions and available methods to address them. Recent advances have led to the rise of outbreak analytics, an emerging data science focused on the technological and methodological aspects of the outbreak data pipeline, from collection to analysis, modelling and reporting to inform outbreak response. In this article, we assess the current state of the field. After laying out the context of outbreak response, we critically review the most common analytics components, their inter-dependencies, data requirements and the type of information they can provide to inform operations in real time. We discuss some challenges and opportunities and conclude on the potential role of outbreak analytics for improving our understanding of, and response to outbreaks of emerging pathogens. This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control‘. This theme issue is linked with the earlier issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’.
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Affiliation(s)
- Jonathan A Polonsky
- 1 Department of Health Emergency Information and Risk Assessment, World Health Organization , Avenue Appia 20, 1211 Geneva , Switzerland.,3 Faculty of Medicine, University of Geneva , 1 rue Michel-Servet, 1211 Geneva , Switzerland
| | - Amrish Baidjoe
- 4 Department of Infectious Disease Epidemiology, School of Public Health, MRC Centre for Global Infectious Disease Analysis, Imperial College London , Medical School Building, St Mary's Campus, Norfolk Place London W2 1PG , UK
| | - Zhian N Kamvar
- 4 Department of Infectious Disease Epidemiology, School of Public Health, MRC Centre for Global Infectious Disease Analysis, Imperial College London , Medical School Building, St Mary's Campus, Norfolk Place London W2 1PG , UK
| | - Anne Cori
- 4 Department of Infectious Disease Epidemiology, School of Public Health, MRC Centre for Global Infectious Disease Analysis, Imperial College London , Medical School Building, St Mary's Campus, Norfolk Place London W2 1PG , UK
| | - Kara Durski
- 2 Department of Infectious Hazard Management, World Health Organization , Avenue Appia 20, 1211 Geneva , Switzerland
| | - W John Edmunds
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,6 Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK
| | - Rosalind M Eggo
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,6 Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK
| | - Sebastian Funk
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,6 Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK
| | - Laurent Kaiser
- 3 Faculty of Medicine, University of Geneva , 1 rue Michel-Servet, 1211 Geneva , Switzerland
| | - Patrick Keating
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,8 UK Public Health Rapid Support Team , London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT , UK
| | - Olivier le Polain de Waroux
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,8 UK Public Health Rapid Support Team , London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT , UK.,9 Public Health England , Wellington House, 133-155 Waterloo Road, London SE1 8UG , UK
| | - Michael Marks
- 7 Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK
| | - Paula Moraga
- 10 Centre for Health Informatics, Computing and Statistics (CHICAS), Lancaster Medical School, Lancaster University , Lancaster LA1 4YW , UK
| | - Oliver Morgan
- 1 Department of Health Emergency Information and Risk Assessment, World Health Organization , Avenue Appia 20, 1211 Geneva , Switzerland
| | - Pierre Nouvellet
- 4 Department of Infectious Disease Epidemiology, School of Public Health, MRC Centre for Global Infectious Disease Analysis, Imperial College London , Medical School Building, St Mary's Campus, Norfolk Place London W2 1PG , UK.,11 School of Life Sciences, University of Sussex , Sussex House, Brighton BN1 9RH , UK
| | - Ruwan Ratnayake
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,6 Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK
| | - Chrissy H Roberts
- 7 Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK
| | - Jimmy Whitworth
- 5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,8 UK Public Health Rapid Support Team , London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT , UK
| | - Thibaut Jombart
- 4 Department of Infectious Disease Epidemiology, School of Public Health, MRC Centre for Global Infectious Disease Analysis, Imperial College London , Medical School Building, St Mary's Campus, Norfolk Place London W2 1PG , UK.,5 Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine , Keppel St, London WC1E 7HT , UK.,8 UK Public Health Rapid Support Team , London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT , UK
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18
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Cavany SM, España G, Lloyd AL, Waller LA, Kitron U, Astete H, Elson WH, Vazquez-Prokopec GM, Scott TW, Morrison AC, Reiner Jr. RC, Perkins TA. Optimizing the deployment of ultra-low volume and targeted indoor residual spraying for dengue outbreak response. PLoS Comput Biol 2020; 16:e1007743. [PMID: 32310958 PMCID: PMC7200023 DOI: 10.1371/journal.pcbi.1007743] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 05/05/2020] [Accepted: 02/24/2020] [Indexed: 02/03/2023] Open
Abstract
Recent years have seen rising incidence of dengue and large outbreaks of Zika and chikungunya, which are all caused by viruses transmitted by Aedes aegypti mosquitoes. In most settings, the primary intervention against Aedes-transmitted viruses is vector control, such as indoor, ultra-low volume (ULV) spraying. Targeted indoor residual spraying (TIRS) has the potential to more effectively impact Aedes-borne diseases, but its implementation requires careful planning and evaluation. The optimal time to deploy these interventions and their relative epidemiological effects are, however, not well understood. We used an agent-based model of dengue virus transmission calibrated to data from Iquitos, Peru to assess the epidemiological effects of these interventions under differing strategies for deploying them. Specifically, we compared strategies where spray application was initiated when incidence rose above a threshold based on incidence in recent years to strategies where spraying occurred at the same time(s) each year. In the absence of spraying, the model predicted 361,000 infections [inter-quartile range (IQR): 347,000-383,000] in the period 2000-2010. The ULV strategy with the fewest median infections was spraying twice yearly, in March and October, which led to a median of 172,000 infections [IQR: 158,000-183,000], a 52% reduction from baseline. Compared to spraying once yearly in September, the best threshold-based strategy utilizing ULV had fewer median infections (254,000 vs. 261,000), but required more spraying (351 vs. 274 days). For TIRS, the best strategy was threshold-based, which led to the fewest infections of all strategies tested (9,900; [IQR: 8,720-11,400], a 94% reduction), and required fewer days spraying than the equivalent ULV strategy (280). Although spraying twice each year is likely to avert the most infections, our results indicate that a threshold-based strategy can become an alternative to better balance the translation of spraying effort into impact, particularly if used with a residual insecticide.
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Affiliation(s)
- Sean M. Cavany
- Department of Biological Sciences & Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Guido España
- Department of Biological Sciences & Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Alun L. Lloyd
- Department of Mathematics & Biomathematics Graduate Program, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Lance A. Waller
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
| | - Uriel Kitron
- Department of Environmental Sciences, Emory University, Atlanta, Georgia, United States of America
| | | | - William H. Elson
- Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America
| | | | - Thomas W. Scott
- Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America
| | - Amy C. Morrison
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America
| | - Robert C. Reiner Jr.
- Institute of Health Metrics and Evaluation, University of Washington, Seattle, Washington, United States of America
| | - T. Alex Perkins
- Department of Biological Sciences & Eck Institute of Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
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19
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Bitsouni V, Lycett S, Opriessnig T, Doeschl-Wilson A. Predicting vaccine effectiveness in livestock populations: A theoretical framework applied to PRRS virus infections in pigs. PLoS One 2019; 14:e0220738. [PMID: 31469850 PMCID: PMC6716781 DOI: 10.1371/journal.pone.0220738] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 07/21/2019] [Indexed: 12/13/2022] Open
Abstract
Vaccines remain one of the main tools to control infectious diseases in domestic livestock. Although a plethora of veterinary vaccines are on the market and routinely applied to protect animals against infection with particular pathogens, the disease in question often continues to persist, sometimes at high prevalence. The limited effectiveness of certain vaccines in the field leaves open questions regarding the required properties that an effective vaccine should have, as well as the most efficient vaccination strategy for achieving the intended goal of vaccination programmes. To date a systematic approach for studying the combined effects of different types of vaccines and vaccination strategies is lacking. In this paper, we develop a theoretical framework for modelling the epidemiological consequences of vaccination with imperfect vaccines of various types, administered using different strategies to herds with different replacement rates and heterogeneity in vaccine responsiveness. Applying the model to the Porcine Reproductive and Respiratory Syndrome (PRRS), which despite routine vaccination remains one of the most significant endemic swine diseases worldwide, we then examine the influence of these diverse factors alone and in combination, on within-herd virus transmission. We derive threshold conditions for preventing infection invasion in the case of imperfect vaccines inducing limited sterilizing immunity. The model developed in this study has practical implications for the development of vaccines and vaccination programmes in livestock populations not only for PRRS, but also for other viral infections primarily transmitted by direct contact.
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Affiliation(s)
- Vasiliki Bitsouni
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush Campus, Midlothian, Edinburgh, Scotland, United Kingdom
- * E-mail: ,
| | - Samantha Lycett
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush Campus, Midlothian, Edinburgh, Scotland, United Kingdom
| | - Tanja Opriessnig
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush Campus, Midlothian, Edinburgh, Scotland, United Kingdom
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America
| | - Andrea Doeschl-Wilson
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush Campus, Midlothian, Edinburgh, Scotland, United Kingdom
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20
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Hagedorn BL, Dabbagh A, McCarthy KA. The cost saving opportunity of introducing a card review into measles-containing vaccination campaigns. Vaccine 2019; 37:6093-6101. [PMID: 31471145 DOI: 10.1016/j.vaccine.2019.08.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 10/26/2022]
Abstract
Measles vaccination is a cost-effective way to prevent infection and reduce mortality and morbidity. However, in countries with fragile routine immunization infrastructure, coverage rates are still low and supplementary immunization campaigns (SIAs) are used to reach previously unvaccinated children. During campaigns, vaccine is generally administered to every child, regardless of their vaccination status and as a result, there is the possibility that a child that is already immune to measles (i.e. who has had 2+ vaccinations) would receive an unnecessary dose, resulting in excess cost. Selective vaccination has been proposed as one solution to this; children who were able to provide documentation of previous vaccination would not be vaccinated repeatedly. While this would result in reduced vaccine and supply cost, it would also require additional staff time and increased social mobilization investment, potentially outweighing the benefits. We utilize Monte Carlo simulation to assess under what conditions a selective vaccination policy would indeed result in net savings. We demonstrate that cost savings are possible in contexts with a high joint probability of an individual child having both 2+ previous measles doses and also an available record. We also find that the magnitude of net cost savings is highly dependent on whether a country is using measles-only or measles-rubella vaccine and on the required skill set of the individual who would review the previous vaccination records.
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Affiliation(s)
| | - Alya Dabbagh
- Department of Immunization, Vaccines, and Biologicals, World Health Organization, Avenue Appia 20, 1211 Genève, Switzerland
| | - Kevin A McCarthy
- Institute for Disease Modeling, 3150 139th Ave SE, Bellevue, WA 98005, USA
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21
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Gastañaduy PA, Banerjee E, DeBolt C, Bravo-Alcántara P, Samad SA, Pastor D, Rota PA, Patel M, Crowcroft NS, Durrheim DN. Public health responses during measles outbreaks in elimination settings: Strategies and challenges. Hum Vaccin Immunother 2018; 14:2222-2238. [PMID: 29932850 PMCID: PMC6207419 DOI: 10.1080/21645515.2018.1474310] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 04/19/2018] [Accepted: 05/03/2018] [Indexed: 02/08/2023] Open
Abstract
In late September 2016, the Americas became the first region in the world to have eliminated endemic transmission of measles virus. Several other countries have also verified measles elimination, and countries in all six World Health Organization regions have adopted measles elimination goals. The public health strategies used to respond to measles outbreaks in elimination settings are thus becoming relevant to more countries. This review highlights the strategies used to limit measles spread in elimination settings: (1) assembly of an outbreak control committee; (2) isolation of measles cases while infectious; (3) exclusion and quarantining of individuals without evidence of immunity; (4) vaccination of susceptible individuals; (5) use of immunoglobulin to prevent measles in exposed susceptible high-risk persons; (6) and maintaining laboratory proficiency for confirmation of measles. Deciding on the extent of containment efforts should be based on the expected benefit of reactive interventions, balanced against the logistical challenges in implementing them.
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Affiliation(s)
- Paul A. Gastañaduy
- Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Emily Banerjee
- Vaccine Preventable Disease Surveillance Unit, Minnesota Department of Health, St. Paul, MN, USA
| | - Chas DeBolt
- Vaccine-Preventable Diseases, Washington State Department of Health, Shoreline, WA, USA
| | - Pamela Bravo-Alcántara
- Comprehensive Family Immunization Unit, Pan American Health Organization, Washington, DC, USA
| | | | - Desiree Pastor
- Comprehensive Family Immunization Unit, Pan American Health Organization, Washington, DC, USA
| | - Paul A. Rota
- Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Manisha Patel
- Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Natasha S. Crowcroft
- Public Health Ontario, Toronto, ON, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
| | - David N. Durrheim
- School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia
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22
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Hagan JE, Greiner A, Luvsansharav UO, Lake J, Lee C, Pastore R, Takashima Y, Sarankhuu A, Demberelsuren S, Smith R, Park B, Goodson JL. Use of a Diagonal Approach to Health System Strengthening and Measles Elimination after a Large Nationwide Outbreak in Mongolia. Emerg Infect Dis 2018; 23. [PMID: 29155667 PMCID: PMC5711310 DOI: 10.3201/eid2313.170594] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Measles is a highly transmissible infectious disease that causes serious illness and death worldwide. Efforts to eliminate measles through achieving high immunization coverage, well-performing surveillance systems, and rapid and effective outbreak response mechanisms while strategically engaging and strengthening health systems have been termed a diagonal approach. In March 2015, a large nationwide measles epidemic occurred in Mongolia, 1 year after verification of measles elimination in this country. A multidisciplinary team conducted an outbreak investigation that included a broad health system assessment, organized around the Global Health Security Agenda framework of Prevent-Detect-Respond, to provide recommendations for evidence-based interventions to interrupt the epidemic and strengthen the overall health system to prevent future outbreaks of measles and other epidemic-prone infectious threats. This investigation demonstrated the value of evaluating elements of the broader health system in investigating measles outbreaks and the need for using a diagonal approach to achieving sustainable measles elimination.
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23
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Measles outbreak risk in Pakistan: exploring the potential of combining vaccination coverage and incidence data with novel data-streams to strengthen control. Epidemiol Infect 2018; 146:1575-1583. [PMID: 29860954 PMCID: PMC6090714 DOI: 10.1017/s0950268818001449] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Although measles incidence has reached historic lows in many parts of the world, the disease still causes substantial morbidity globally. Even where control programs have succeeded in driving measles locally extinct, unless vaccination coverage is maintained at extremely high levels, susceptible numbers may increase sufficiently to spark large outbreaks. Human mobility will drive potentially infectious contacts and interact with the landscape of susceptibility to determine the pattern of measles outbreaks. These interactions have proved difficult to characterise empirically. We explore the degree to which new sources of data combined with existing public health data can be used to evaluate the landscape of immunity and the role of spatial movement for measles introductions by retrospectively evaluating our ability to predict measles outbreaks in vaccinated populations. Using inferred spatial patterns of accumulation of susceptible individuals and travel data, we predicted the timing of epidemics in each district of Pakistan during a large measles outbreak in 2012–2013 with over 30 000 reported cases. We combined these data with mobility data extracted from over 40 million mobile phone subscribers during the same time frame in the country to quantify the role of connectivity in the spread of measles. We investigate how different approaches could contribute to targeting vaccination efforts to reach districts before outbreaks started. While some prediction was possible, accuracy was low and we discuss key uncertainties linked to existing data streams that impede such inference and detail what data might be necessary to robustly infer timing of epidemics.
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24
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Gignoux E, Polonsky J, Ciglenecki I, Bichet M, Coldiron M, Thuambe Lwiyo E, Akonda I, Serafini M, Porten K. Risk factors for measles mortality and the importance of decentralized case management during an unusually large measles epidemic in eastern Democratic Republic of Congo in 2013. PLoS One 2018. [PMID: 29538437 PMCID: PMC5851624 DOI: 10.1371/journal.pone.0194276] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In 2013, a large measles epidemic occurred in the Aketi Health Zone of the Democratic Republic of Congo. We conducted a two-stage, retrospective cluster survey to estimate the attack rate, the case fatality rate, and the measles-specific mortality rate during the epidemic. 1424 households containing 7880 individuals were included. The estimated attack rate was 14.0%, (35.0% among children aged <5 years). The estimated case fatality rate was 4.2% (6.1% among children aged <5 years). Spatial analysis and linear regression showed that younger children, those who did not receive care, and those living farther away from Aketi Hospital early in the epidemic had a higher risk of measles related death. Vaccination coverage prior to the outbreak was low (76%), and a delayed reactive vaccination campaign contributed to the high attack rate. We provide evidences suggesting that a comprehensive case management approach reduced measles fatality during this epidemic in rural, inaccessible resource-poor setting.
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Affiliation(s)
| | | | | | - Mathieu Bichet
- Médecins Sans Frontières, Geneva, Switzerland
- Médecins Sans Frontières, Paris, France
| | | | | | - Innocent Akonda
- Ministère de la Santé Publique, Kinshassa, République Démocratique du Congo
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25
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Willem L, Verelst F, Bilcke J, Hens N, Beutels P. Lessons from a decade of individual-based models for infectious disease transmission: a systematic review (2006-2015). BMC Infect Dis 2017; 17:612. [PMID: 28893198 PMCID: PMC5594572 DOI: 10.1186/s12879-017-2699-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 08/22/2017] [Indexed: 02/18/2023] Open
Abstract
Background Individual-based models (IBMs) are useful to simulate events subject to stochasticity and/or heterogeneity, and have become well established to model the potential (re)emergence of pathogens (e.g., pandemic influenza, bioterrorism). Individual heterogeneity at the host and pathogen level is increasingly documented to influence transmission of endemic diseases and it is well understood that the final stages of elimination strategies for vaccine-preventable childhood diseases (e.g., polio, measles) are subject to stochasticity. Even so it appears IBMs for both these phenomena are not well established. We review a decade of IBM publications aiming to obtain insights in their advantages, pitfalls and rationale for use and to make recommendations facilitating knowledge transfer within and across disciplines. Methods We systematically identified publications in Web of Science and PubMed from 2006-2015 based on title/abstract/keywords screening (and full-text if necessary) to retrieve topics, modeling purposes and general specifications. We extracted detailed modeling features from papers on established vaccine-preventable childhood diseases based on full-text screening. Results We identified 698 papers, which applied an IBM for infectious disease transmission, and listed these in a reference database, describing their general characteristics. The diversity of disease-topics and overall publication frequency have increased over time (38 to 115 annual publications from 2006 to 2015). The inclusion of intervention strategies (8 to 52) and economic consequences (1 to 20) are increasing, to the detriment of purely theoretical explorations. Unfortunately, terminology used to describe IBMs is inconsistent and ambiguous. We retrieved 24 studies on a vaccine-preventable childhood disease (covering 7 different diseases), with publication frequency increasing from the first such study published in 2008. IBMs have been useful to explore heterogeneous between- and within-host interactions, but combined applications are still sparse. The amount of missing information on model characteristics and study design is remarkable. Conclusions IBMs are suited to combine heterogeneous within- and between-host interactions, which offers many opportunities, especially to analyze targeted interventions for endemic infections. We advocate the exchange of (open-source) platforms and stress the need for consistent “branding”. Using (existing) conventions and reporting protocols would stimulate cross-fertilization between research groups and fields, and ultimately policy making in decades to come. Electronic supplementary material The online version of this article (doi:10.1186/s12879-017-2699-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lander Willem
- Centre for Health Economics Research & Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.
| | - Frederik Verelst
- Centre for Health Economics Research & Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - Joke Bilcke
- Centre for Health Economics Research & Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - Niel Hens
- Centre for Health Economics Research & Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.,Interuniversity Institute for Biostatistics and statistical Bioinformatics, UHasselt, Hasselt, Belgium
| | - Philippe Beutels
- Centre for Health Economics Research & Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.,School of Public Health and Community Medicine, The University of New South Wales, Sydney, Australia
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26
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Li S, Ma C, Hao L, Su Q, An Z, Ma F, Xie S, Xu A, Zhang Y, Ding Z, Li H, Cairns L, Wang H, Luo H, Wang N, Li L, Ferrari MJ. Demographic transition and the dynamics of measles in six provinces in China: A modeling study. PLoS Med 2017; 14:e1002255. [PMID: 28376084 PMCID: PMC5380361 DOI: 10.1371/journal.pmed.1002255] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 02/08/2017] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Industrialization and demographic transition generate nonstationary dynamics in human populations that can affect the transmission and persistence of infectious diseases. Decades of increasing vaccination and development have led to dramatic declines in the global burden of measles, but the virus remains persistent in much of the world. Here we show that a combination of demographic transition, as a result of declining birth rates, and reduced measles prevalence, due to improved vaccination, has shifted the age distribution of susceptibility to measles throughout China. METHODS AND FINDINGS We fit a novel time-varying catalytic model to three decades of age-specific measles case reporting in six provinces in China to quantify the change in the age-specific force of infection for measles virus over time. We further quantified the impact of supplemental vaccination campaigns on the reduction of susceptible individuals. The force of infection of measles has declined dramatically (90%-97% reduction in transmission rate) in three industrialized eastern provinces during the last decade, driving a concomitant increase in both the relative proportion and absolute number of adult cases, while three central and western provinces exhibited dynamics consistent with endemic persistence (24%-73% reduction in transmission rate). The reduction in susceptible individuals due to supplemental vaccination campaigns is frequently below the nominal campaign coverage, likely because campaigns necessarily vaccinate those who may already be immune. The impact of these campaigns has significantly improved over time: campaigns prior to 2005 were estimated to have achieved less than 50% reductions in the proportion susceptible in the target age classes, but campaigns from 2005 onwards reduced the susceptible proportion by 32%-87%. A limitation of this study is that it relies on case surveillance, and thus inference may be biased by age-specific variation in measles reporting. CONCLUSIONS The age distribution of measles cases changes in response to both demographic and vaccination processes. Combining both processes in a novel catalytic model, we illustrate that age-specific incidence patterns reveal regional differences in the progress to measles elimination and the impact of vaccination controls in China. The shift in the age distribution of measles susceptibility in response to demographic and vaccination processes emphasizes the importance of progressive control strategies and measures to evaluate program success that anticipate and react to this transition in observed incidence.
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Affiliation(s)
- Sheng Li
- School of Public Health, City University of New York, New York, New York, United States of America
| | - Chao Ma
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Lixin Hao
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Qiru Su
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Zhijie An
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Fubao Ma
- Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, China
| | - Shuyun Xie
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Aiqiang Xu
- Shandong Provincial Center for Disease Control and Prevention, Jinan, China
| | - Yanyang Zhang
- Henan Provincial Center for Disease Control and Prevention, Zhengzhou, China
| | - Zhengrong Ding
- Yunnan Provincial Center for Disease Control and Prevention, Kunming, China
| | - Hui Li
- Gansu Provincial Center for Disease Control and Prevention, Lanzhou, China
| | - Lisa Cairns
- Global Immunization Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Huaqing Wang
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Huiming Luo
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Ning Wang
- Nation Center for AIDS, China Centers for Disease Control and Prevention, Beijing, China
| | - Li Li
- National Immunization Program, China Centers for Disease Control and Prevention, Beijing, China
| | - Matthew J. Ferrari
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, Pennsylvania, United States of America
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27
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Tang X, Geater A, McNeil E, Zhou H, Deng Q, Dong A. Timeliness and completeness of measles vaccination among children in rural areas of Guangxi, China: A stratified three-stage cluster survey. J Epidemiol 2017; 27:317-324. [PMID: 28187960 PMCID: PMC5498417 DOI: 10.1016/j.je.2016.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 08/07/2016] [Indexed: 12/01/2022] Open
Abstract
Background Large-scale outbreaks of measles occurred in 2013 and 2014 in rural Guangxi, a region in Southwest China with high coverage for measles-containing vaccine (MCV). This study aimed to estimate the timely vaccination coverage, the timely-and-complete vaccination coverage, and the median delay period for MCV among children aged 18–54 months in rural Guangxi. Methods Based on quartiles of measles incidence during 2011–2013, a stratified three-stage cluster survey was conducted from June through August 2015. Using weighted estimation and finite population correction, vaccination coverage and 95% confidence intervals (CIs) were calculated. Weighted Kaplan–Meier analyses were used to estimate the median delay periods for the first (MCV1) and second (MCV2) doses of the vaccine. Results A total of 1216 children were surveyed. The timely vaccination coverage rate was 58.4% (95% CI, 54.9%–62.0%) for MCV1, and 76.9% (95% CI, 73.6%–80.0%) for MCV2. The timely-and-complete vaccination coverage rate was 47.4% (95% CI, 44.0%–51.0%). The median delay period was 32 (95% CI, 27–38) days for MCV1, and 159 (95% CI, 118–195) days for MCV2. Conclusions The timeliness and completeness of measles vaccination was low, and the median delay period was long among children in rural Guangxi. Incorporating the timeliness and completeness into official routine vaccination coverage statistics may help appraise the coverage of vaccination in China. The timeliness and completeness of measles vaccination was low. The median delay period of measles vaccination was long among Guangxi children. Regions with higher measles incidence had higher rates of untimely coverage.
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Affiliation(s)
- Xianyan Tang
- Department of Epidemiology & Biostatistics, School of Public Health, Guangxi Medical University, Guangxi Zhuang Autonomous Region, China; Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Thailand
| | - Alan Geater
- Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Thailand.
| | - Edward McNeil
- Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Hat Yai, Thailand
| | - Hongxia Zhou
- Department of Epidemiology & Biostatistics, School of Public Health, Guangxi Medical University, Guangxi Zhuang Autonomous Region, China
| | - Qiuyun Deng
- Institute of Vaccination, Guangxi Center for Disease Control and Prevention, Guangxi Zhuang Autonomous Region, China
| | - Aihu Dong
- Institute of Vaccination, Guangxi Center for Disease Control and Prevention, Guangxi Zhuang Autonomous Region, China
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28
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Buckee CO, Tatem AJ, Metcalf CJE. Seasonal Population Movements and the Surveillance and Control of Infectious Diseases. Trends Parasitol 2016; 33:10-20. [PMID: 27865741 DOI: 10.1016/j.pt.2016.10.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/08/2016] [Accepted: 10/19/2016] [Indexed: 10/20/2022]
Abstract
National policies designed to control infectious diseases should allocate resources for interventions based on regional estimates of disease burden from surveillance systems. For many infectious diseases, however, there is pronounced seasonal variation in incidence. Policy-makers must routinely manage a public health response to these seasonal fluctuations with limited understanding of their underlying causes. Two complementary and poorly described drivers of seasonal disease incidence are the mobility and aggregation of human populations, which spark outbreaks and sustain transmission, respectively, and may both exhibit distinct seasonal variations. Here we highlight the key challenges that seasonal migration creates when monitoring and controlling infectious diseases. We discuss the potential of new data sources in accounting for seasonal population movements in dynamic risk mapping strategies.
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Affiliation(s)
- Caroline O Buckee
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, USA; Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public Health, Boston, USA.
| | - Andrew J Tatem
- Flowminder Foundation, Stockholm, Sweden; WorldPop, Department of Geography and Environment, University of Southampton, Southampton, UK
| | - C Jessica E Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, USA; Office of Population Research, Woodrow Wilson School, Princeton University, Princeton, USA
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29
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Bharti N, Djibo A, Tatem AJ, Grenfell BT, Ferrari MJ. Measuring populations to improve vaccination coverage. Sci Rep 2016; 5:34541. [PMID: 27703191 PMCID: PMC5050518 DOI: 10.1038/srep34541] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/14/2016] [Indexed: 11/09/2022] Open
Abstract
In low-income settings, vaccination campaigns supplement routine immunization but often fail to achieve coverage goals due to uncertainty about target population size and distribution. Accurate, updated estimates of target populations are rare but critical; short-term fluctuations can greatly impact population size and susceptibility. We use satellite imagery to quantify population fluctuations and the coverage achieved by a measles outbreak response vaccination campaign in urban Niger and compare campaign estimates to measurements from a post-campaign survey. Vaccine coverage was overestimated because the campaign underestimated resident numbers and seasonal migration further increased the target population. We combine satellite-derived measurements of fluctuations in population distribution with high-resolution measles case reports to develop a dynamic model that illustrates the potential improvement in vaccination campaign coverage if planners account for predictable population fluctuations. Satellite imagery can improve retrospective estimates of vaccination campaign impact and future campaign planning by synchronizing interventions with predictable population fluxes.
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Affiliation(s)
- Nita Bharti
- Biology Department; Center for Infectious Disease Dynamics, Pennsylvania State University, University Park PA, USA.,Woods Institute for the Environment, Stanford University, Stanford CA, USA
| | | | - Andrew J Tatem
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.,WorldPop, Department of Geography, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
| | - Bryan T Grenfell
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.,Department of Ecology and Evolutionary Biology; Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton NJ, USA
| | - Matthew J Ferrari
- Biology Department; Center for Infectious Disease Dynamics, Pennsylvania State University, University Park PA, USA.,Department of Statistics, Pennsylvania State University, University Park PA, USA
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30
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Lessler J, Metcalf CJE, Cutts FT, Grenfell BT. Impact on Epidemic Measles of Vaccination Campaigns Triggered by Disease Outbreaks or Serosurveys: A Modeling Study. PLoS Med 2016; 13:e1002144. [PMID: 27727285 PMCID: PMC5058560 DOI: 10.1371/journal.pmed.1002144] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 09/02/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Routine vaccination supplemented by planned campaigns occurring at 2-5 y intervals is the core of current measles control and elimination efforts. Yet, large, unexpected outbreaks still occur, even when control measures appear effective. Supplementing these activities with mass vaccination campaigns triggered when low levels of measles immunity are observed in a sample of the population (i.e., serosurveys) or incident measles cases occur may provide a way to limit the size of outbreaks. METHODS AND FINDINGS Measles incidence was simulated using stochastic age-structured epidemic models in settings conducive to high or low measles incidence, roughly reflecting demographic contexts and measles vaccination coverage of four heterogeneous countries: Nepal, Niger, Yemen, and Zambia. Uncertainty in underlying vaccination rates was modeled. Scenarios with case- or serosurvey-triggered campaigns reaching 20% of the susceptible population were compared to scenarios without triggered campaigns. The best performing of the tested case-triggered campaigns prevent an average of 28,613 (95% CI 25,722-31,505) cases over 15 y in our highest incidence setting and 599 (95% CI 464-735) cases in the lowest incidence setting. Serosurvey-triggered campaigns can prevent 89,173 (95% CI, 86,768-91,577) and 744 (612-876) cases, respectively, but are triggered yearly in high-incidence settings. Triggered campaigns reduce the highest cumulative incidence seen in simulations by up to 80%. While the scenarios considered in this strategic modeling exercise are reflective of real populations, the exact quantitative interpretation of the results is limited by the simplifications in country structure, vaccination policy, and surveillance system performance. Careful investigation into the cost-effectiveness in different contexts would be essential before moving forward with implementation. CONCLUSIONS Serologically triggered campaigns could help prevent severe epidemics in the face of epidemiological and vaccination uncertainty. Hence, small-scale serology may serve as the basis for effective adaptive public health strategies, although, in high-incidence settings, case-triggered approaches are likely more efficient.
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Affiliation(s)
- Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
| | - C. Jessica E. Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Office of Population Research, Princeton University, Princeton, New Jersey, United States of America
- Fogarty International Center, Bethesda, Maryland, United States of America
| | - Felicity T. Cutts
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Bryan T. Grenfell
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- Fogarty International Center, Bethesda, Maryland, United States of America
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31
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Thompson KM, Duintjer Tebbens RJ. Framework for Optimal Global Vaccine Stockpile Design for Vaccine-Preventable Diseases: Application to Measles and Cholera Vaccines as Contrasting Examples. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2016; 36:1487-1509. [PMID: 25109229 DOI: 10.1111/risa.12265] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Managing the dynamics of vaccine supply and demand represents a significant challenge with very high stakes. Insufficient vaccine supplies can necessitate rationing, lead to preventable adverse health outcomes, delay the achievements of elimination or eradication goals, and/or pose reputation risks for public health authorities and/or manufacturers. This article explores the dynamics of global vaccine supply and demand to consider the opportunities to develop and maintain optimal global vaccine stockpiles for universal vaccines, characterized by large global demand (for which we use measles vaccines as an example), and nonuniversal (including new and niche) vaccines (for which we use oral cholera vaccine as an example). We contrast our approach with other vaccine stockpile optimization frameworks previously developed for the United States pediatric vaccine stockpile to address disruptions in supply and global emergency response vaccine stockpiles to provide on-demand vaccines for use in outbreaks. For measles vaccine, we explore the complexity that arises due to different formulations and presentations of vaccines, consideration of rubella, and the context of regional elimination goals. We conclude that global health policy leaders and stakeholders should procure and maintain appropriate global vaccine rotating stocks for measles and rubella vaccine now to support current regional elimination goals, and should probably also do so for other vaccines to help prevent and control endemic or epidemic diseases. This work suggests the need to better model global vaccine supplies to improve efficiency in the vaccine supply chain, ensure adequate supplies to support elimination and eradication initiatives, and support progress toward the goals of the Global Vaccine Action Plan.
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Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Inc, 10524 Moss Park Rd., Ste. 204-364, Orlando, FL, USA
- University of Central Florida, College of Medicine, Orlando, FL, USA
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32
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Thompson KM, Kisjes KH. Modeling Measles Transmission in the North American Amish and Options for Outbreak Response. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2016; 36:1404-1417. [PMID: 26103154 DOI: 10.1111/risa.12440] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Revised: 05/20/2015] [Accepted: 05/24/2015] [Indexed: 06/04/2023]
Abstract
Measles outbreaks in the United States continue to occur in subpopulations with sufficient numbers of undervaccinated individuals, with a 2014 outbreak in Amish communities in Ohio pushing the annual cases to the highest national number reported in the last 20 years. We adapted an individual-based model developed to explore potential poliovirus transmission in the North American Amish to characterize a 1988 measles outbreak in the Pennsylvania Amish and the 2014 outbreak in the Ohio Amish. We explored the impact of the 2014 outbreak response compared to no or partial response. Measles can spread very rapidly in an underimmunized subpopulation like the North American Amish, with the potential for national spread within a year or so in the absence of outbreak response. Vaccination efforts significantly reduced the transmission of measles and the expected number of cases. Until global eradication, measles importations will continue to pose a threat to clusters of underimmunized individuals in the United States. Aggressive outbreak response efforts in Ohio probably prevented widespread transmission of measles within the entire North American Amish.
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Affiliation(s)
- Kimberly M Thompson
- Kid Risk, Inc, Orlando, FL, USA
- College of Medicine, University of Central Florida, Orlando, FL, USA
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33
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Thompson KM. Evolution and Use of Dynamic Transmission Models for Measles and Rubella Risk and Policy Analysis. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2016; 36:1383-1403. [PMID: 27277138 DOI: 10.1111/risa.12637] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The devastation caused by periodic measles outbreaks motivated efforts over more than a century to mathematically model measles disease and transmission. Following the identification of rubella, which similarly presents with fever and rash and causes congenital rubella syndrome (CRS) in infants born to women first infected with rubella early in pregnancy, modelers also began to characterize rubella disease and transmission. Despite the relatively large literature, no comprehensive review to date provides an overview of dynamic transmission models for measles and rubella developed to support risk and policy analysis. This systematic review of the literature identifies quantitative measles and/or rubella dynamic transmission models and characterizes key insights relevant for prospective modeling efforts. Overall, measles and rubella represent some of the relatively simplest viruses to model due to their ability to impact only humans and the apparent life-long immunity that follows survival of infection and/or protection by vaccination, although complexities arise due to maternal antibodies and heterogeneity in mixing and some models considered potential waning immunity and reinfection. This review finds significant underreporting of measles and rubella infections and widespread recognition of the importance of achieving and maintaining high population immunity to stop and prevent measles and rubella transmission. The significantly lower transmissibility of rubella compared to measles implies that all countries could eliminate rubella and CRS by using combination of measles- and rubella-containing vaccines (MRCVs) as they strive to meet regional measles elimination goals, which leads to the recommendation of changing the formulation of national measles-containing vaccines from measles only to MRCV as the standard of care.
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Wesolowski A, Mensah K, Brook CE, Andrianjafimasy M, Winter A, Buckee CO, Razafindratsimandresy R, Tatem AJ, Heraud JM, Metcalf CJE. Introduction of rubella-containing-vaccine to Madagascar: implications for roll-out and local elimination. J R Soc Interface 2016; 13:20151101. [PMID: 27122178 PMCID: PMC4874430 DOI: 10.1098/rsif.2015.1101] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/07/2016] [Indexed: 12/01/2022] Open
Abstract
Few countries in Africa currently include rubella-containing vaccination (RCV) in their immunization schedule. The Global Alliance for Vaccines Initiative (GAVI) recently opened a funding window that has motivated more widespread roll-out of RCV. As countries plan RCV introductions, an understanding of the existing burden, spatial patterns of vaccine coverage, and the impact of patterns of local extinction and reintroduction for rubella will be critical to developing effective programmes. As one of the first countries proposing RCV introduction in part with GAVI funding, Madagascar provides a powerful and timely case study. We analyse serological data from measles surveillance systems to characterize the epidemiology of rubella in Madagascar. Combining these results with data on measles vaccination delivery, we develop an age-structured model to simulate rubella vaccination scenarios and evaluate the dynamics of rubella and the burden of congenital rubella syndrome (CRS) across Madagascar. We additionally evaluate the drivers of spatial heterogeneity in age of infection to identify focal locations where vaccine surveillance should be strengthened and where challenges to successful vaccination introduction are expected. Our analyses indicate that characteristics of rubella in Madagascar are in line with global observations, with an average age of infection near 7 years, and an impact of frequent local extinction with reintroductions causing localized epidemics. Modelling results indicate that introduction of RCV into the routine programme alone may initially decrease rubella incidence but then result in cumulative increases in the burden of CRS in some regions (and transient increases in this burden in many regions). Deployment of RCV with regular supplementary campaigns will mitigate these outcomes. Results suggest that introduction of RCV offers a potential for elimination of rubella in Madagascar, but also emphasize both that targeted vaccination is likely to be a lynchpin of this success, and the public health vigilance that this introduction will require.
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Affiliation(s)
- Amy Wesolowski
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA Center for Communicable Disease Dynamics, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Keitly Mensah
- Virology Unit and Measles and Rubella WHO National Reference Laboratory, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Cara E Brook
- Department of Geography and Environment, University of Southampton, Southampton, UK
| | - Miora Andrianjafimasy
- Virology Unit and Measles and Rubella WHO National Reference Laboratory, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Amy Winter
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
| | - Caroline O Buckee
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, USA Center for Communicable Disease Dynamics, Harvard T. H. Chan School of Public Health, Boston, MA, USA Office of Population Research, Woodrow Wilson School, Princeton University, Princeton, NJ, USA
| | - Richter Razafindratsimandresy
- Virology Unit and Measles and Rubella WHO National Reference Laboratory, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Andrew J Tatem
- Department of Geography and Environment, University of Southampton, Southampton, UK Fogarty International Center, National Institutes of Health, Bethesda, MD, USA Flowminder Foundation, Stockholm, Sweden
| | - Jean-Michel Heraud
- Virology Unit and Measles and Rubella WHO National Reference Laboratory, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - C Jessica E Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA Office of Population Research, Woodrow Wilson School, Princeton University, Princeton, NJ, USA
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Dalziel BD, Bjørnstad ON, van Panhuis WG, Burke DS, Metcalf CJE, Grenfell BT. Persistent Chaos of Measles Epidemics in the Prevaccination United States Caused by a Small Change in Seasonal Transmission Patterns. PLoS Comput Biol 2016; 12:e1004655. [PMID: 26845437 PMCID: PMC4741526 DOI: 10.1371/journal.pcbi.1004655] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 11/15/2015] [Indexed: 11/19/2022] Open
Abstract
Epidemics of infectious diseases often occur in predictable limit cycles. Theory suggests these cycles can be disrupted by high amplitude seasonal fluctuations in transmission rates, resulting in deterministic chaos. However, persistent deterministic chaos has never been observed, in part because sufficiently large oscillations in transmission rates are uncommon. Where they do occur, the resulting deep epidemic troughs break the chain of transmission, leading to epidemic extinction, even in large cities. Here we demonstrate a new path to locally persistent chaotic epidemics via subtle shifts in seasonal patterns of transmission, rather than through high-amplitude fluctuations in transmission rates. We base our analysis on a comparison of measles incidence in 80 major cities in the prevaccination era United States and United Kingdom. Unlike the regular limit cycles seen in the UK, measles cycles in US cities consistently exhibit spontaneous shifts in epidemic periodicity resulting in chaotic patterns. We show that these patterns were driven by small systematic differences between countries in the duration of the summer period of low transmission. This example demonstrates empirically that small perturbations in disease transmission patterns can fundamentally alter the regularity and spatiotemporal coherence of epidemics.
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Affiliation(s)
- Benjamin D. Dalziel
- Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America
| | - Ottar N. Bjørnstad
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Willem G. van Panhuis
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Donald S. Burke
- Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - C. Jessica E. Metcalf
- Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America
| | - Bryan T. Grenfell
- Department of Ecology and Evolutionary Biology and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Parham PE, Waldock J, Christophides GK, Hemming D, Agusto F, Evans KJ, Fefferman N, Gaff H, Gumel A, LaDeau S, Lenhart S, Mickens RE, Naumova EN, Ostfeld RS, Ready PD, Thomas MB, Velasco-Hernandez J, Michael E. Climate, environmental and socio-economic change: weighing up the balance in vector-borne disease transmission. Philos Trans R Soc Lond B Biol Sci 2015; 370:rstb.2013.0551. [PMID: 25688012 DOI: 10.1098/rstb.2013.0551] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems.
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Affiliation(s)
- Paul E Parham
- Department of Public Health and Policy, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3GL, UK Grantham Institute for Climate Change, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Joanna Waldock
- The Cyprus Institute, Nicosia, Cyprus Imperial College London, London SW7 2AZ, UK
| | | | - Deborah Hemming
- Meteorological Office Hadley Centre, UK Meteorological Office, Fitzroy Road, Exeter, EX1 3PB, UK
| | - Folashade Agusto
- Department of Mathematics, Austin Peay State University, Clarksville, TN 37044, USA
| | - Katherine J Evans
- Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Nina Fefferman
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, USA
| | - Holly Gaff
- Department of Biological Sciences, Old Dominium University, Norfolk, VA 23529, USA
| | - Abba Gumel
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1904, USA School of Mathematical and Natural Sciences, Arizona State University, Phoenix, AZ 85069-7100, USA
| | - Shannon LaDeau
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Suzanne Lenhart
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996-1300, USA
| | - Ronald E Mickens
- Department of Physics, Clark Atlanta University, PO Box 172, Atlanta, GA 30314, USA
| | - Elena N Naumova
- Department of Civil and Environmental Engineering, Tufts University School of Engineering, Medford, MA 02155, USA
| | - Richard S Ostfeld
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Paul D Ready
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Matthew B Thomas
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jorge Velasco-Hernandez
- Universidad Nacional Autnoma de Mexico Institute of Mathematics Mexico City, Distrito Federal, Mexico
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369, USA
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Abstract
Reactive vaccination has recently been adopted as an outbreak response tool for cholera and other infectious diseases. Owing to the global shortage of oral cholera vaccine, health officials must quickly decide who and where to distribute limited vaccine. Targeted vaccination in transmission hotspots (i.e. areas with high transmission efficiency) may be a potential approach to efficiently allocate vaccine, however its effectiveness will likely be context-dependent. We compared strategies for allocating vaccine across multiple areas with heterogeneous transmission efficiency. We constructed metapopulation models of a cholera-like disease and compared simulated epidemics where: vaccine is targeted at areas of high or low transmission efficiency, where vaccine is distributed across the population, and where no vaccine is used. We find that connectivity between populations, transmission efficiency, vaccination timing and the amount of vaccine available all shape the performance of different allocation strategies. In highly connected settings (e.g. cities) when vaccinating early in the epidemic, targeting limited vaccine at transmission hotspots is often optimal. Once vaccination is delayed, targeting the hotspot is rarely optimal, and strategies that either spread vaccine between areas or those targeted at non-hotspots will avert more cases. Although hotspots may be an intuitive outbreak control target, we show that, in many situations, the hotspot-epidemic proceeds so fast that hotspot-targeted reactive vaccination will prevent relatively few cases, and vaccination shared across areas where transmission can be sustained is often best.
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Affiliation(s)
- Andrew S Azman
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, 615 North Wolfe St., Baltimore, MD 21205, USA
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Chowell G, Viboud C. Ebola vaccine trials: a race against the clock. THE LANCET. INFECTIOUS DISEASES 2015; 15:624-6. [DOI: 10.1016/s1473-3099(15)70159-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Shea K, Tildesley MJ, Runge MC, Fonnesbeck CJ, Ferrari MJ. Adaptive management and the value of information: learning via intervention in epidemiology. PLoS Biol 2014; 12:e1001970. [PMID: 25333371 PMCID: PMC4204804 DOI: 10.1371/journal.pbio.1001970] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 09/05/2014] [Indexed: 11/18/2022] Open
Abstract
This Research Article explores the benefits of applying Adaptive Management approaches to disease outbreaks, finding that formally integrating science and policy allows one to reduce uncertainty and improve disease management outcomes. Optimal intervention for disease outbreaks is often impeded by severe scientific uncertainty. Adaptive management (AM), long-used in natural resource management, is a structured decision-making approach to solving dynamic problems that accounts for the value of resolving uncertainty via real-time evaluation of alternative models. We propose an AM approach to design and evaluate intervention strategies in epidemiology, using real-time surveillance to resolve model uncertainty as management proceeds, with foot-and-mouth disease (FMD) culling and measles vaccination as case studies. We use simulations of alternative intervention strategies under competing models to quantify the effect of model uncertainty on decision making, in terms of the value of information, and quantify the benefit of adaptive versus static intervention strategies. Culling decisions during the 2001 UK FMD outbreak were contentious due to uncertainty about the spatial scale of transmission. The expected benefit of resolving this uncertainty prior to a new outbreak on a UK-like landscape would be £45–£60 million relative to the strategy that minimizes livestock losses averaged over alternate transmission models. AM during the outbreak would be expected to recover up to £20.1 million of this expected benefit. AM would also recommend a more conservative initial approach (culling of infected premises and dangerous contact farms) than would a fixed strategy (which would additionally require culling of contiguous premises). For optimal targeting of measles vaccination, based on an outbreak in Malawi in 2010, AM allows better distribution of resources across the affected region; its utility depends on uncertainty about both the at-risk population and logistical capacity. When daily vaccination rates are highly constrained, the optimal initial strategy is to conduct a small, quick campaign; a reduction in expected burden of approximately 10,000 cases could result if campaign targets can be updated on the basis of the true susceptible population. Formal incorporation of a policy to update future management actions in response to information gained in the course of an outbreak can change the optimal initial response and result in significant cost savings. AM provides a framework for using multiple models to facilitate public-health decision making and an objective basis for updating management actions in response to improved scientific understanding. If the response to a disease outbreak is poorly managed, lives may be lost and money wasted unnecessarily. Lack of knowledge about the disease dynamics, and about the effects of our control strategies on those dynamics, means that it is difficult to do the best job possible managing such epidemiological problems. Here, we present an adaptive management approach that allows researchers to use knowledge gained during an outbreak to update ongoing interventions, thereby translating scientific discovery into improved policy. We explore the implications of adaptive management for foot-and-mouth disease outbreaks in livestock and for measles vaccination strategies in humans. In these two particular cases, planning to update management actions leads to the recommendation of a less aggressive initial approach than if changes in management are not anticipated. We demonstrate expected savings of up to £20 million in terms of lower livestock losses to culling in a foot-and-mouth outbreak based on the dynamics observed in the UK in 2001. Similarly, up to 10,000 cases could have been averted in a measles outbreak like the one observed in Malawi in 2010. Adaptive management allows real-time improvement of our understanding, and hence of management efforts, with potentially significant positive financial and health benefits.
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Affiliation(s)
- Katriona Shea
- Department of Biology and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
| | - Michael J. Tildesley
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Michael C. Runge
- US Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland, United States of America
| | - Christopher J. Fonnesbeck
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Matthew J. Ferrari
- Department of Biology and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
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Ferrari MJ, Fermon F, Nackers F, Llosa A, Magone C, Grais RF. Time is (still) of the essence: quantifying the impact of emergency meningitis vaccination response in Katsina State, Nigeria. Int Health 2014; 6:282-90. [PMID: 25193978 DOI: 10.1093/inthealth/ihu062] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND In 2009, a large meningitis A epidemic affected a broad region of northern Nigeria and southern Niger, resulting in more than 75 000 cases and 4000 deaths. In collaboration with state and federal agencies, Médecins Sans Frontières (MSF) intervened with a large-scale vaccination campaign using polysaccharide vaccine. Here the authors analyze the impact (cases averted) of the vaccination response as a function of the timing and coverage achieved. METHODS Phenomenological epidemic models were fitted to replicate meningitis surveillance data from the Nigerian Ministry of Health/WHO surveillance system and from reinforced surveillance conducted by MSF in both vaccinated and unvaccinated areas using a dynamic, state-space framework to account for under-reporting of cases. RESULTS The overall impact of the vaccination campaigns (reduction in meningitis cases) in Katsina State, northern Nigeria, ranged from 4% to 12%. At the local level, vaccination reduced cases by as much as 50% when campaigns were conducted early in the epidemic. CONCLUSIONS Reactive vaccination with polysaccharide vaccine during meningitis outbreaks can significantly reduce the case burden when conducted early and comprehensively. Introduction of the conjugate MenAfriVac vaccine has reduced rates of disease caused by serogroup A Neisseria meningitidis in the region. Despite this, reactive campaigns with polysaccharide vaccine remain a necessary and important tool for meningitis outbreak response.
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Affiliation(s)
- Matthew J Ferrari
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802 USA
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Mancini S, Coldiron ME, Ronsse A, Ilunga BK, Porten K, Grais RF. Description of a large measles epidemic in Democratic Republic of Congo, 2010-2013. Confl Health 2014; 8:9. [PMID: 25053974 PMCID: PMC4105555 DOI: 10.1186/1752-1505-8-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 06/24/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Although measles mortality has declined dramatically in Sub-Saharan Africa, measles remains a major public health problem in countries like the Democratic Republic of Congo (DRC). Here, we describe the large measles epidemic that occurred in the Democratic Republic of Congo between 2010 and 2013 using data from the national surveillance system as well as vaccine coverage surveys to provide a snapshot of the epidemiology of measles in DRC. METHODS Standardized national surveillance data were used to describe measles cases from 2010 to 2013. Attack rates and case fatality ratios were calculated and the temporal and spatial evolution of the epidemic described. Data on laboratory confirmation and vaccination coverage surveys as a part of routine program monitoring are also presented. FINDINGS Between week 1 of 2010 and week 45 of 2013, a total of 294,455 cases and 5,045 deaths were reported. The cumulative attack rate (AR) was 0.4%. The Case Fatality Ratio (CFR) was 1.7% among cases reported in health structures through national surveillance. A total of 186,178 cases (63%) were under 5 years old, representing an estimated AR of 1.4% in this age group. Following the first mass vaccination campaigns, weekly reported cases decreased by 21.5%. Results of post-vaccination campaign coverage surveys indicated sub-optimal (under 95%) vaccination coverage among children surveyed. CONCLUSIONS The data reported here highlight the need to seek additional means to reinforce routine immunization as well as ensure the timely implementation of Supplementary Immunization Activities to prevent large and repeated measles epidemics in DRC. Although reactive campaigns were conducted in response to the epidemic, strategies to ensure that children are vaccinated in the routine system remains the foundation of measles control.
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Affiliation(s)
- Silvia Mancini
- Epicentre, 8 Rue Saint Sabin, Paris 75011, France
- Médecins Sans Frontières, Via Magenta 5, Rome, Italy
| | | | | | - Benoît Kebela Ilunga
- Ministry of Health, Av. De la Justice 39, Gombe I, Kinshasa, Democratic Republic of Congo
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Isere E, Fatiregun A. Measles case-based surveillance and outbreak response in Nigeria; an update for clinicians and public health professionals. Ann Ib Postgrad Med 2014; 12:15-21. [PMID: 25332696 PMCID: PMC4201929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The Federal Ministry of Health recommendations for response during measles epidemics in Nigeria previously focused on case management using antibiotics and Vitamin. A supplements and did not include outbreak response immunization (ORI) campaigns. However, with the revision of the existing national technical guideline on measles casebased surveillance and outbreak response in Nigeria in 2012 in line with the World Health Organization recommendation on response to measles outbreak in measles mortality reduction settings, there is a need to update members of the Nigerian public health community on these revisions to ensure appropriate implementation and compliance. This article therefore seeks to provide clinicians and other public health professionals in Nigeria with updates on recent developments in measles case-based surveillance and outbreak response in Nigeria.
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Affiliation(s)
- E.E Isere
- Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - A.A Fatiregun
- Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
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Minetti A, Hurtado N, Grais RF, Ferrari M. Reaching hard-to-reach individuals: Nonselective versus targeted outbreak response vaccination for measles. Am J Epidemiol 2014; 179:245-51. [PMID: 24131555 PMCID: PMC3873105 DOI: 10.1093/aje/kwt236] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Current mass vaccination campaigns in measles outbreak response are nonselective with respect to the immune status of individuals. However, the heterogeneity in immunity, due to previous vaccination coverage or infection, may lead to potential bias of such campaigns toward those with previous high access to vaccination and may result in a lower-than-expected effective impact. During the 2010 measles outbreak in Malawi, only 3 of the 8 districts where vaccination occurred achieved a measureable effective campaign impact (i.e., a reduction in measles cases in the targeted age groups greater than that observed in nonvaccinated districts). Simulation models suggest that selective campaigns targeting hard-to-reach individuals are of greater benefit, particularly in highly vaccinated populations, even for low target coverage and with late implementation. However, the choice between targeted and nonselective campaigns should be context specific, achieving a reasonable balance of feasibility, cost, and expected impact. In addition, it is critical to develop operational strategies to identify and target hard-to-reach individuals.
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Affiliation(s)
| | | | | | - Matthew Ferrari
- Correspondence to Dr. Matthew Ferrari, Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, PA 16802 (e-mail: )
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Alberti KP, King LA, Burny ME, Ilunga BK, Grais RF. Reactive vaccination as an effective tool for measles outbreak control in measles mortality reduction settings, Democratic Republic of Congo, 2005-2006. Int Health 2013; 2:65-8. [PMID: 24037053 DOI: 10.1016/j.inhe.2009.12.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
New WHO guidelines for measles outbreak response in measles mortality reduction settings now include reactive vaccination for outbreaks. Here we used surveillance data and vaccine coverage surveys following two mass vaccine campaigns in the Democratic Republic of Congo, to show the impact of reactive vaccination on reducing cases during outbreaks. The number of measles cases reported was collected via the national surveillance system. Following vaccination campaigns, two-stage cluster sampling surveys were used to evaluate pre and post campaign coverage. In Matadi, 1035 cases were reported from 24 October 2005 to 19 February 2006 and in Mbuji Mayi, 4734 cases were reported from 3 October 2005 to 30 April 2006. Following the mass vaccination campaign, coverage rose from 87.5% (95% CI 87.2-87.8) to 97.1% (95% CI 96.9-97.3) in Matadi and from 74.0% (95% CI 70.9-77.0) to 96.5% (95% CI: 95.7-97.2) in Mbuji Mayi. Weekly reported cases reduced respectively by 89.3% and 68.9% in the 3 weeks following the mass vaccination campaigns. The introduction of reactive vaccination for measles outbreak control provides an additional tool to help reduce the impact of outbreaks. Our experience shows that this type of intervention is feasible and effective even when baseline vaccination coverage is > 70%.
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Rosewell A, Clark G, Mabong P, Ropa B, Posanai E, Man NWY, Dutta SR, Wickramasinghe W, Qi L, Ng JC, Mola G, Zwi AB, MacIntyre CR. Concurrent outbreaks of cholera and peripheral neuropathy associated with high mortality among persons internally displaced by a volcanic eruption. PLoS One 2013; 8:e72566. [PMID: 24023752 PMCID: PMC3759368 DOI: 10.1371/journal.pone.0072566] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 07/10/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In October 2004, Manam Island volcano in Papua New Guinea erupted, causing over 10 000 villagers to flee to internally displaced person (IDP) camps, including 550 from Dugulaba village. Following violence over land access in March 2010, the IDPs fled the camps, and four months later concurrent outbreaks of acute watery diarrhea and unusual neurological complaints were reported in this population. MATERIALS AND METHODS A retrospective case-control study was conducted to identify the risk factors for peripheral neuropathy. Rectal swabs were collected from cases of acute watery diarrhea. Hair and serum metals and metalloids were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). RESULTS There were 17 deaths among the 550 village inhabitants during the outbreak period at a crude mortality rate 21-fold that of a humanitarian crisis. Vibrio cholerae O1 El Tor Ogawa was confirmed among the population. Access to community-level rehydration was crucial to mortality. Peripheral neuropathy was diagnosed among cases with neurological symptoms. A balanced diet was significantly protective against neuropathy. A dose-response relationship was seen between peripheral neuropathy and a decreasing number of micronutrient- rich foods in the diet. Deficiencies in copper, iron, selenium and zinc were identified among the cases of peripheral neuropathy. CONCLUSIONS Cholera likely caused the mostly preventable excess mortality. Peripheral neuropathy was not caused by cholera, but cholera may worsen existing nutritional deficiencies. The peripheral neuropathy was likely caused by complex micronutrient deficiencies linked to non-diversified diets that potentially increased the vulnerability of this population, however a new zinc-associated neuropathy could not be ruled out. Reoccurrence can be prevented by addressing the root cause of displacement and ensuring access to arable land and timely resettlement.
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Affiliation(s)
- Alexander Rosewell
- World Health Organization, Port Moresby, National Capital District (NCD), Papua New Guinea
- School of Public Health and Community Medicine, The University of New South Wales, New South Wales, Sydney, NSW, Australia
- * E-mail:
| | - Geoff Clark
- World Health Organization, Port Moresby, National Capital District (NCD), Papua New Guinea
| | - Paul Mabong
- Provincial Health Office, Madang, Madang Province, Papua New Guinea
| | - Berry Ropa
- National Department of Health, Port Moresby, NCD, Papua New Guinea
| | - Enoch Posanai
- National Department of Health, Port Moresby, NCD, Papua New Guinea
| | - Nicola W. Y. Man
- School of Public Health and Community Medicine, The University of New South Wales, New South Wales, Sydney, NSW, Australia
| | - Samir R. Dutta
- Pathology Department, Port Moresby General Hospital, Port Moresby, NCD, Papua New Guinea
| | - Wasa Wickramasinghe
- The University of Queensland, National Research Centre for Environmental Toxicology, Coopers Plains, Queensland, Australia
| | - Lixia Qi
- The University of Queensland, National Research Centre for Environmental Toxicology, Coopers Plains, Queensland, Australia
| | - Jack C. Ng
- The University of Queensland, National Research Centre for Environmental Toxicology, Coopers Plains, Queensland, Australia
| | - Glen Mola
- University of Papua New Guinea, Port Moresby, NCD, Papua New Guinea
| | - Anthony B. Zwi
- School of Public Health and Community Medicine, The University of New South Wales, New South Wales, Sydney, NSW, Australia
| | - C. Raina MacIntyre
- School of Public Health and Community Medicine, The University of New South Wales, New South Wales, Sydney, NSW, Australia
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46
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Ferrari MJ, Grenfell BT, Strebel PM. Think globally, act locally: the role of local demographics and vaccination coverage in the dynamic response of measles infection to control. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120141. [PMID: 23798689 PMCID: PMC3720039 DOI: 10.1098/rstb.2012.0141] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The global reduction of the burden of morbidity and mortality owing to measles has been a major triumph of public health. However, the continued persistence of measles infection probably not only reflects local variation in progress towards vaccination target goals, but may also reflect local variation in dynamic processes of transmission, susceptible replenishment through births and stochastic local extinction. Dynamic models predict that vaccination should increase the mean age of infection and increase inter-annual variability in incidence. Through a comparative approach, we assess national-level patterns in the mean age of infection and measles persistence. We find that while the classic predictions do hold in general, the impact of vaccination on the age distribution of cases and stochastic fadeout are mediated by local birth rate. Thus, broad-scale vaccine coverage goals are unlikely to have the same impact on the interruption of measles transmission in all demographic settings. Indeed, these results suggest that the achievement of further measles reduction or elimination goals is likely to require programmatic and vaccine coverage goals that are tailored to local demographic conditions.
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Affiliation(s)
- M J Ferrari
- Center for Infectious Disease Dynamics, Departments of Biology and Statistics, The Pennsylvania State University, University Park, PA 16802, USA.
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47
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Klepac P, Metcalf CJE, McLean AR, Hampson K. Towards the endgame and beyond: complexities and challenges for the elimination of infectious diseases. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120137. [PMID: 23798686 PMCID: PMC3720036 DOI: 10.1098/rstb.2012.0137] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Successful control measures have interrupted the local transmission of human infectious diseases such as measles, malaria and polio, and saved and improved billions of lives. Similarly, control efforts have massively reduced the incidence of many infectious diseases of animals, such as rabies and rinderpest, with positive benefits for human health and livelihoods across the globe. However, disease elimination has proven an elusive goal, with only one human and one animal pathogen globally eradicated. As elimination targets expand to regional and even global levels, hurdles may emerge within the endgame when infections are circulating at very low levels, turning the last mile of these public health marathons into the longest mile. In this theme issue, we bring together recurring challenges that emerge as we move towards elimination, highlighting the unanticipated consequences of particular ecologies and pathologies of infection, and approaches to their management.
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Affiliation(s)
- Petra Klepac
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
| | | | - Angela R. McLean
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX13 PS, UK
| | - Katie Hampson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
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48
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Minetti A, Kagoli M, Katsulukuta A, Huerga H, Featherstone A, Chiotcha H, Noel D, Bopp C, Sury L, Fricke R, Iscla M, Hurtado N, Ducomble T, Nicholas S, Kabuluzi S, Grais RF, Luquero FJ. Lessons and challenges for measles control from unexpected large outbreak, Malawi. Emerg Infect Dis 2013; 19:202-9. [PMID: 23343504 PMCID: PMC3559033 DOI: 10.3201/eid1902.120301] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Supplementary immunization activities are crucial to reduce the number of susceptible children. Despite high reported coverage for routine and supplementary immunization, in 2010 in Malawi, a large measles outbreak occurred that comprised 134,000 cases and 304 deaths. Although the highest attack rates were for young children (2.3%, 7.6%, and 4.5% for children <6, 6–8, and 9–11 months, respectively), persons >15 years of age were highly affected (1.0% and 0.4% for persons 15–19 and >19 years, respectively; 28% of all cases). A survey in 8 districts showed routine coverage of 95.0% for children 12–23 months; 57.9% for children 9–11 months; and 60.7% for children covered during the last supplementary immunization activities in 2008. Vaccine effectiveness was 83.9% for 1 dose and 90.5% for 2 doses. A continuous accumulation of susceptible persons during the past decade probably accounts for this outbreak. Countries en route to measles elimination, such as Malawi, should improve outbreak preparedness. Timeliness and the population chosen are crucial elements for reactive campaigns.
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49
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Sume GE, Fouda AAB, Kobela M, Nguelé S, Emah I, Atem P. A locally initiated and executed measles outbreak response immunization campaign in the nylon health district, Douala Cameroon 2011. BMC Res Notes 2013; 6:100. [PMID: 23497712 PMCID: PMC3607843 DOI: 10.1186/1756-0500-6-100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 03/12/2013] [Indexed: 11/10/2022] Open
Abstract
The Cameroon health system is divided into central, intermediate and peripheral levels. Of the 43 health districts with a measles outbreak in Cameroon in 2011, only the Nylon Health District organized a documented outbreak response immunization. We present the methods and results of the response campaign solely shouldered by the district and intermediate level. The risk group, targets and neighborhoods to be vaccinated were identified after a detailed analysis of initial cases. The intermediate level defined strategies, provided logistics, capacity building and 41% of the operational budget while 59% was completed by the peripheral level. Microsoft Office Excel 2007 was used to estimate coverage rates and to draw an epidemic curve. The response immunization campaign was organized on the 14th epidemiological week, 10 weeks after the onset of the outbreak which ended 11 weeks thereafter. A total of 15867(108.5%) children aged 9-59 months were vaccinated in five health areas at a direct cost (vaccines excluded) of 71.34FCFA ($0.143) per vaccinated child. An additional 824 children aged 9-59 months were vaccinated around the residence of notified cases in neighborhoods which were not involved in the response campaign. The number of cases after the response campaign was lower than before. Once vaccines are available, prompt outbreak response campaigns can be organized at operational level to obtain commendable results instead of depending solely on international organizations or central levels. Decision makers at the intermediate and operational levels should redeploy available funds during emergencies to prevent the development of extreme public health conditions.
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Affiliation(s)
- Gerald Etapelong Sume
- Regional Delegation of Public Health for the Littoral, PO Box 106, Douala, Cameroon.
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50
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Bonačić Marinović AA, Swaan C, Wichmann O, van Steenbergen J, Kretzschmar M. Effectiveness and timing of vaccination during school measles outbreak. Emerg Infect Dis 2013; 18:1405-13. [PMID: 22931850 PMCID: PMC3437694 DOI: 10.3201/eid1809.111578] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Implementing a vaccination campaign during an outbreak can effectively reduce the outbreak size.
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Affiliation(s)
- Axel Antonio Bonačić Marinović
- Center for Infectious Disease Control, National Institute for Public Health and the Environment-RIVM, PO Box 1, 3720 BA Bilthoven, the Netherlands.
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