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Chua H, Feng S, Lewnard JA, Sullivan SG, Blyth CC, Lipsitch M, Cowling BJ. The Use of Test-negative Controls to Monitor Vaccine Effectiveness: A Systematic Review of Methodology. Epidemiology 2020; 31:43-64. [PMID: 31609860 PMCID: PMC6888869 DOI: 10.1097/ede.0000000000001116] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND The test-negative design is an increasingly popular approach for estimating vaccine effectiveness (VE) due to its efficiency. This review aims to examine published test-negative design studies of VE and to explore similarities and differences in methodological choices for different diseases and vaccines. METHODS We conducted a systematic search on PubMed, Web of Science, and Medline, for studies reporting the effectiveness of any vaccines using a test-negative design. We screened titles and abstracts and reviewed full texts to identify relevant articles. We created a standardized form for each included article to extract information on the pathogen of interest, vaccine(s) being evaluated, study setting, clinical case definition, choices of cases and controls, and statistical approaches used to estimate VE. RESULTS We identified a total of 348 articles, including studies on VE against influenza virus (n = 253), rotavirus (n = 48), pneumococcus (n = 24), and nine other pathogens. Clinical case definitions used to enroll patients were similar by pathogens of interest but the sets of symptoms that defined them varied substantially. Controls could be those testing negative for the pathogen of interest, those testing positive for nonvaccine type of the pathogen of interest, or a subset of those testing positive for alternative pathogens. Most studies controlled for age, calendar time, and comorbidities. CONCLUSIONS Our review highlights similarities and differences in the application of the test-negative design that deserve further examination. If vaccination reduces disease severity in breakthrough infections, particular care must be taken in interpreting vaccine effectiveness estimates from test-negative design studies.
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Affiliation(s)
- Huiying Chua
- From the World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Shuo Feng
- From the World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
| | - Joseph A Lewnard
- Division of Epidemiology, School of Public Health, University of California, Berkeley, Berkeley, CA
| | - Sheena G Sullivan
- WHO Collaborating Centre for Reference and Research on Influenza, Royal Melbourne Hospital, and Doherty Department, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA
- Centre for Epidemiology and Biostatistics, School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Christopher C Blyth
- Division of Paediatrics, School of Medicine, Faculty of Health and Medical Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia
- Department of Infectious Diseases, Perth Children's Hospital, Perth, Western Australia, Australia
| | - Marc Lipsitch
- Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA
- Center for Communicable Disease Dynamics, Harvard T. H. Chan School of Public Health, Boston, MA
| | - Benjamin J Cowling
- From the World Health Organization Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, The University of Hong Kong, Hong Kong Special Administrative Region, China
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Abstract
BACKGROUND Central nervous system infections are an important cause of childhood morbidity and mortality in high HIV-prevalence settings of Africa. We evaluated the epidemiology of pediatric meningitis in Botswana during the rollout of antiretroviral therapy, pneumococcal conjugate vaccine and Haemophilus influenzae type B (HiB) vaccine. METHODS We performed a cross-sectional study of children (<15 years old) evaluated for meningitis by cerebrospinal fluid (CSF) examination from 2000 to 2015, with complete national records for 2013-2014. Clinical and laboratory characteristics of microbiologically confirmed and culture-negative meningitis were described and incidence of Streptococcus pneumoniae, H. influenzae and cryptococcal meningitis was estimated for 2013-2014. RESULTS A total of 6796 unique cases were identified. Median age was 1 year [interquartile range 0-3]; 10.4% (435/4186) of children with available HIV-related records were known HIV-infected. Overall, 30.4% (2067/6796) had abnormal CSF findings (positive microbiologic testing or CSF pleocytosis). Ten percent (651/6796) had a confirmed microbiologic diagnosis; including 26.9% (175/651) Cryptococcus, 18.9% (123/651) S. pneumoniae, 20.3% (132/651) H. influenzae and 1.1% (7/651) Mycobacterium tuberculosis. During 2013-2014, national cryptococcal meningitis incidence was 1.3 cases per 100,000 person-years (95% confidence interval, 0.8-2.1) and pneumococcal meningitis incidence 0.7 per 100,000 person-years (95% confidence interval, 0.3-1.3), with no HiB meningitis diagnosed. CONCLUSIONS Following HiB vaccination, a marked decline in microbiologically confirmed cases of H. influenzae meningitis occurred. Cryptococcal meningitis remains the most common confirmed etiology, demonstrating gaps in prevention-of-mother-to-child transmission and early HIV diagnosis. The high proportion of abnormal CSF samples with no microbiologic diagnosis highlights limitation in available diagnostics.
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Verani JR, Baqui AH, Broome CV, Cherian T, Cohen C, Farrar JL, Feikin DR, Groome MJ, Hajjeh RA, Johnson HL, Madhi SA, Mulholland K, O'Brien KL, Parashar UD, Patel MM, Rodrigues LC, Santosham M, Scott JA, Smith PG, Sommerfelt H, Tate JE, Victor JC, Whitney CG, Zaidi AK, Zell ER. Case-control vaccine effectiveness studies: Data collection, analysis and reporting results. Vaccine 2017; 35:3303-3308. [PMID: 28442230 PMCID: PMC7008029 DOI: 10.1016/j.vaccine.2017.04.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 12/25/2022]
Abstract
The case-control methodology is frequently used to evaluate vaccine effectiveness post-licensure. The results of such studies provide important insight into the level of protection afforded by vaccines in a 'real world' context, and are commonly used to guide vaccine policy decisions. However, the potential for bias and confounding are important limitations to this method, and the results of a poorly conducted or incorrectly interpreted case-control study can mislead policies. In 2012, a group of experts met to review recent experience with case-control studies evaluating vaccine effectiveness; we summarize the recommendations of that group regarding best practices for data collection, analysis, and presentation of the results of case-control vaccine effectiveness studies. Vaccination status is the primary exposure of interest, but can be challenging to assess accurately and with minimal bias. Investigators should understand factors associated with vaccination as well as the availability of documented vaccination status in the study context; case-control studies may not be a valid method for evaluating vaccine effectiveness in settings where many children lack a documented immunization history. To avoid bias, it is essential to use the same methods and effort gathering vaccination data from cases and controls. Variables that may confound the association between illness and vaccination are also important to capture as completely as possible, and where relevant, adjust for in the analysis according to the analytic plan. In presenting results from case-control vaccine effectiveness studies, investigators should describe enrollment among eligible cases and controls as well as the proportion with no documented vaccine history. Emphasis should be placed on confidence intervals, rather than point estimates, of vaccine effectiveness. Case-control studies are a useful approach for evaluating vaccine effectiveness; however careful attention must be paid to the collection, analysis and presentation of the data in order to best inform evidence-based vaccine policies.
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Affiliation(s)
- Jennifer R Verani
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA.
| | - Abdullah H Baqui
- International Center for Maternal and Newborn Health, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - Claire V Broome
- Rollins School of Public Health Emory University, 1518 Clifton Rd, Atlanta, GA, USA
| | - Thomas Cherian
- Department of Immunizations, Vaccines and Biologicals, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
| | - Cheryl Cohen
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, 1 Modderfontein Rd, Sandringham, Johannesburg, South Africa
| | - Jennifer L Farrar
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
| | - Daniel R Feikin
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA; International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - Michelle J Groome
- Respiratory and Meningeal Pathogens Unit, University of Witwatersrand, Richard Ward, 1 Jan Smuts Ave, Braamfontein, Johannesburg, South Africa
| | - Rana A Hajjeh
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
| | - Hope L Johnson
- Monitoring & Evaluation, Policy & Performance, GAVI Alliance, Chemin des Mines 2, 1202 Geneva, Switzerland
| | - Shabir A Madhi
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, 1 Modderfontein Rd, Sandringham, Johannesburg, South Africa; Respiratory and Meningeal Pathogens Unit, University of Witwatersrand, Richard Ward, 1 Jan Smuts Ave, Braamfontein, Johannesburg, South Africa
| | - Kim Mulholland
- Murdoch Children's Research Institute, Royal Children's Hospital, 50 Flemington Rd, Parkville VIC 3052, Australia; Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
| | - Katherine L O'Brien
- International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - Umesh D Parashar
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
| | - Manish M Patel
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
| | - Laura C Rodrigues
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
| | - Mathuram Santosham
- International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - J Anthony Scott
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK; KEMRI-Wellcome Trust Research Programme, PO Box 230-80108, Kilifi, Kenya
| | - Peter G Smith
- MRC Tropical Epidemiology Group, London School of Tropical Medicine and Hygiene, London, UK
| | - Halvor Sommerfelt
- Centre of Intervention Science in Maternal and Child Health and Centre for International Health, University of Bergen, PO Box 7800, Bergen, Norway; Department of International Public Health, Norwegian Institute of Public Health, PO Box 4404, Nydalen, Oslo, Norway
| | - Jacqueline E Tate
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
| | | | - Cynthia G Whitney
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
| | | | - Elizabeth R Zell
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA
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Verani JR, Baqui AH, Broome CV, Cherian T, Cohen C, Farrar JL, Feikin DR, Groome MJ, Hajjeh RA, Johnson HL, Madhi SA, Mulholland K, O'Brien KL, Parashar UD, Patel MM, Rodrigues LC, Santosham M, Scott JA, Smith PG, Sommerfelt H, Tate JE, Victor JC, Whitney CG, Zaidi AK, Zell ER. Case-control vaccine effectiveness studies: Preparation, design, and enrollment of cases and controls. Vaccine 2017; 35:3295-3302. [PMID: 28442231 PMCID: PMC7007298 DOI: 10.1016/j.vaccine.2017.04.037] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 01/01/2023]
Abstract
Case-control studies are commonly used to evaluate effectiveness of licensed vaccines after deployment in public health programs. Such studies can provide policy-relevant data on vaccine performance under ‘real world’ conditions, contributing to the evidence base to support and sustain introduction of new vaccines. However, case-control studies do not measure the impact of vaccine introduction on disease at a population level, and are subject to bias and confounding, which may lead to inaccurate results that can misinform policy decisions. In 2012, a group of experts met to review recent experience with case-control studies evaluating the effectiveness of several vaccines; here we summarize the recommendations of that group regarding best practices for planning, design and enrollment of cases and controls. Rigorous planning and preparation should focus on understanding the study context including healthcare-seeking and vaccination practices. Case-control vaccine effectiveness studies are best carried out soon after vaccine introduction because high coverage creates strong potential for confounding. Endpoints specific to the vaccine target are preferable to non-specific clinical syndromes since the proportion of non-specific outcomes preventable through vaccination may vary over time and place, leading to potentially confusing results. Controls should be representative of the source population from which cases arise, and are generally recruited from the community or health facilities where cases are enrolled. Matching of controls to cases for potential confounding factors is commonly used, although should be reserved for a limited number of key variables believed to be linked to both vaccination and disease. Case-control vaccine effectiveness studies can provide information useful to guide policy decisions and vaccine development, however rigorous preparation and design is essential.
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Affiliation(s)
- Jennifer R Verani
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA.
| | - Abdullah H Baqui
- International Center for Maternal and Newborn Health, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - Claire V Broome
- Rollins School of Public Health Emory University, 1518 Clifton Rd, Atlanta, GA, USA
| | - Thomas Cherian
- Department of Immunizations, Vaccines and Biologicals, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
| | - Cheryl Cohen
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, 1 Modderfontein Road, Sandringham, Johannesburg, South Africa
| | - Jennifer L Farrar
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
| | - Daniel R Feikin
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA; International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - Michelle J Groome
- Respiratory and Meningeal Pathogens Unit, University of Witwatersrand, Richard Ward, 1 Jan Smuts Ave, Braamfontein, Johannesburg, South Africa
| | - Rana A Hajjeh
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
| | - Hope L Johnson
- Monitoring & Evaluation, Policy & Performance, GAVI Alliance, Chemin des Mines 2, 1202 Geneva, Switzerland
| | - Shabir A Madhi
- Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases, 1 Modderfontein Road, Sandringham, Johannesburg, South Africa; Respiratory and Meningeal Pathogens Unit, University of Witwatersrand, Richard Ward, 1 Jan Smuts Ave, Braamfontein, Johannesburg, South Africa
| | - Kim Mulholland
- Murdoch Children's Research Institute, Royal Children's Hospital, 50 Flemington Rd, Parkville, VIC 3052, Australia; Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
| | - Katherine L O'Brien
- International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - Umesh D Parashar
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
| | - Manish M Patel
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
| | - Laura C Rodrigues
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
| | - Mathuram Santosham
- International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD, USA
| | - J Anthony Scott
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK; KEMRI-Wellcome Trust Research Programme, P.O. Box 230-80108, Kilifi, Kenya
| | - Peter G Smith
- MRC Tropical Epidemiology Group, London School of Tropical Medicine and Hygiene, London, UK
| | - Halvor Sommerfelt
- Centre of Intervention Science in Maternal and Child Health and Centre for International Health, University of Bergen, P.O. Box 7800, Bergen, Norway; Department of International Public Health, Norwegian Institute of Public Health, PO Box 4404, Nydalen, Oslo, Norway
| | - Jacqueline E Tate
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
| | | | - Cynthia G Whitney
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
| | | | - Elizabeth R Zell
- National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd., Atlanta, GA, USA
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Baird FJ, Lopata AL. The dichotomy of pathogens and allergens in vaccination approaches. Front Microbiol 2014; 5:365. [PMID: 25076945 PMCID: PMC4100532 DOI: 10.3389/fmicb.2014.00365] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/30/2014] [Indexed: 12/30/2022] Open
Abstract
Traditional prophylactic vaccination to prevent illness is the primary objective of many research activities worldwide. The golden age of vaccination began with an approach called variolation in ancient China and the evolution of vaccines still continues today with modern developments such as the production of Gardasil(TM) against HPV and cervical cancer. The historical aspect of how different forms of vaccination have changed the face of medicine and communities is important as it dictates our future approaches on both a local and global scale. From the eradication of smallpox to the use of an experimental vaccine to save a species, this review will explore these successes in infectious disease vaccination and also discuss a few significant failures which have hampered our efforts to eradicate certain diseases. The second part of the review will explore designing a prophylactic vaccine for the growing global health concern that is allergy. Allergies are an emerging global health burden. Of particular concern is the rise of food allergies in developed countries where 1 in 10 children is currently affected. The formation of an allergic response results from the recognition of a foreign component by our immune system that is usually encountered on a regular basis. This may be a dust-mite or a prawn but this inappropriate immune response can result in a life-time of food avoidance and lifestyle restrictions. These foreign components are very similar to antigens derived from infectious pathogens. The question arises: should the allergy community be focussing on protective measures rather than ongoing therapeutic interventions to deal with these chronic inflammatory conditions? We will explore the difficulties and benefits of prophylactic vaccination against various allergens by means of genetic technology that will dictate how vaccination against allergens could be utilized in the near future.
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Affiliation(s)
- Fiona J. Baird
- Centre for Biodiscovery & Molecular Development of Therapeutics, Centre for Biosecurity in Tropical Infectious Diseases, Australian Institute of Tropical Health & Medicine, James Cook UniversityTownsville, QLD, Australia
- Molecular Immunology Group, School of Pharmacy and Molecular Biology, James Cook UniversityTownsville, QLD, Australia
| | - Andreas L. Lopata
- Centre for Biodiscovery & Molecular Development of Therapeutics, Centre for Biosecurity in Tropical Infectious Diseases, Australian Institute of Tropical Health & Medicine, James Cook UniversityTownsville, QLD, Australia
- Molecular Immunology Group, School of Pharmacy and Molecular Biology, James Cook UniversityTownsville, QLD, Australia
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Abstract
Vaccine probe studies have emerged in the past 15 years as a useful way to characterise disease. By contrast, traditional studies of vaccines focus on defining the vaccine effectiveness or efficacy. The underlying basis for the vaccine probe approach is that the difference in disease burden between vaccinated and unvaccinated individuals can be ascribed to the vaccine-specific pathogen. Vaccine probe studies can increase understanding of a vaccine's public health value. For instance, even when a vaccine has a seemingly low efficacy, a high baseline disease incidence can lead to a large vaccine-preventable disease burden and thus that population-based vaccine introduction would be justified. So far, vaccines have been used as probes to characterise disease syndromes caused by Haemophilus influenzae type b, pneumococcus, rotavirus, and early infant influenza. However, vaccine probe studies have enormous potential and could be used more widely in epidemiology, for example, to define the vaccine-preventable burden of malaria, typhoid, paediatric influenza, and dengue, and to identify causal interactions between different pathogens.
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Affiliation(s)
- Daniel R Feikin
- International Vaccine Access Center, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA; Division of Preparedness and Emerging Infections, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA.
| | - J Anthony G Scott
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; London School of Hygiene and Tropical Medicine, London, UK
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Gessner BD. Haemophilus influenzaetype b vaccine impact in resource-poor settings in Asia and Africa. Expert Rev Vaccines 2014; 8:91-102. [DOI: 10.1586/14760584.8.1.91] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Effectiveness of Haemophilus influenzae type b vaccines administered according to various schedules: systematic review and meta-analysis of observational data. Pediatr Infect Dis J 2013; 32:1261-9. [PMID: 23811746 DOI: 10.1097/inf.0b013e3182a14e57] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Conjugate vaccines against Haemophilus influenzae type b (Hib) are widely used. The full implications of Hib vaccination schedule for vaccine effectiveness (VE) are unclear. METHODS We searched the literature for observational studies reporting the effectiveness of conjugate Hib vaccines administered according to different schedules. We summarized dose-specific VE estimates, where appropriate, using random effects meta-analysis. RESULTS Thirty-one eligible articles (reporting 30 studies conducted in 17 countries) were identified. Meta-analysis of case-control studies using community controls produced VE estimates against Hib meningitis of 55% (95% confidence interval: 2-80%, based on 3 studies), 96% (86-99%, 3 studies) and 96% (86-99%, 4 studies) after 1, 2 and 3 doses of vaccines other than the polyribosyl ribitol phosphate outer membrane protein vaccine. Estimates were similar using hospital controls. VE against invasive Hib disease in case-control studies was estimated as 59% (30-76%, 3 studies) and 97% (87-99%, 3 studies) for 1 and 3 doses (insufficient data were identified to estimate 2-dose VE). Point estimates from 2 studies suggested VE>90% after 1 dose of the polyribosyl ribitol phosphate outer membrane protein vaccine, but meta-analysis was not possible. Using data from 4 cohort studies, 3-dose VE was estimated as 94% (88-97%). There was some evidence that Hib vaccine was less effective when administered with acellular (rather than whole cell) pertussis vaccine. Weak evidence from 2 studies suggested that a booster confers some additional protection following full primary vaccination and may compensate for an incomplete primary series. CONCLUSIONS Observational data suggest that ≥2 doses of Hib vaccine are required for high effectiveness, but do not strongly favor any particular schedule.
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Davis S, Feikin D, Johnson HL. The effect of Haemophilus influenzae type B and pneumococcal conjugate vaccines on childhood meningitis mortality: a systematic review. BMC Public Health 2013; 13 Suppl 3:S21. [PMID: 24564188 PMCID: PMC3847464 DOI: 10.1186/1471-2458-13-s3-s21] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Two of the most prevalent causes of severe bacterial meningitis in children, Haemophilus influenzae type B (Hib) and Streptococcus pneumoniae, are preventable by existing vaccines increasingly available in developing countries. Our objective was to estimate the dose-specific effect of Hib and pneumococcal conjugate vaccines (PCV) on childhood meningitis mortality in low-income countries for use in the Lives Saved Tool (LiST). Methods We systematically searched and reviewed published vaccine efficacy trials and observational studies reporting the effect of Hib or PCV vaccines on organism-specific meningitis, bacterial meningitis and all-cause meningitis incidence and mortality among children less than five years old in low- and middle-income countries. Data collection and quality assessments were performed using standardized guidelines. For outcomes available across multiple studies (≥2) and approximating meningitis mortality, we pooled estimates reporting dose-specific effects using random effects meta-analytic methods, then combined these with meningitis etiology data to determine the preventable fraction of childhood meningitis mortality for inclusion in LiST. Results We identified 18 studies of Hib conjugate vaccines reporting relevant meningitis morbidity and mortality outcomes (2 randomized controlled trials [RCTs], 16 observational studies) but few provided dose-specific effects. A meta-analysis of four case-control studies examined the dose-specific effect of Hib conjugate vaccines on Hib meningitis morbidity (1 dose: RR=0.64, 95% CI 0.38-1.06; 2 doses: RR=0.09, 95% CI 0.03-0.27; 3 doses: RR=0.06, 95% CI 0.02-0.22), consistent with results from single RCTs. Pooled estimates of two RCTs provided evidence for the effect of three doses of PCV on vaccine-serotype meningitis morbidity (RR=0.16, 95% CI 0.02-1.20). We considered these outcomes of severe disease as proxy estimates for meningitis mortality and combined the estimates of protective effects with meningitis etiology data to provide an estimate of the preventable fraction of childhood meningitis mortality with three doses of Hib (38-43%) and pneumococcal conjugate vaccines (28-35%) for use in LiST. Conclusions Few RCTs or vaccine effectiveness studies evaluated the dose-specific impact of Hib and PCV vaccines on childhood meningitis mortality, necessitating use of proxy measures to estimate population impact in LiST. Our analysis indicates that approximately three-quarters of meningitis deaths are preventable with existing Hib and PCV vaccines.
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Ba O, Fleming JA, Dieye Y, wa Mutombo BM, Ba M, Cisse MF, Diallo AG, Sow I, Slack MPE, Faye PC, Ba M, Diallo N, Weiss NS. Hospital surveillance of childhood bacterial meningitis in Senegal and the introduction of Haemophilus influenzae type b conjugate vaccine. Am J Trop Med Hyg 2010; 83:1330-5. [PMID: 21118944 PMCID: PMC2990054 DOI: 10.4269/ajtmh.2010.10-0346] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 09/28/2010] [Indexed: 11/07/2022] Open
Abstract
Bacterial meningitis is an important cause of morbidity and mortality in children living in low-resource settings. Pediatric bacterial meningitis cases < 5 years of age were identified through a regional hospital surveillance system for 3 years after introduction of routine immunization with Haemophilus influenzae type b (Hib) conjugate vaccine in Senegal in July 2005. Cases from the national pediatric hospital were also tracked from 2002 to 2008. The regional surveillance system recorded 1,711 suspected pediatric bacterial meningitis cases. Of 214 laboratory-confirmed cases, 108 (50%) were caused by Streptococcus pneumoniae, 42 (20%) to Hib, and 13 (6%) to Neisseria meningitidis. There was a 98% reduction in the number of hospitalized Hib meningitis cases from Dakar Region in 2008 compared with 2002. The surveillance system provides important information to the Ministry of Health as they consider self-funding Hib vaccine and introducing pneumococcal vaccine.
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O'Loughlin RE, Edmond K, Mangtani P, Cohen AL, Shetty S, Hajjeh R, Mulholland K. Methodology and measurement of the effectiveness of Haemophilus influenzae type b vaccine: systematic review. Vaccine 2010; 28:6128-36. [PMID: 20655402 DOI: 10.1016/j.vaccine.2010.06.107] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 06/12/2010] [Accepted: 06/30/2010] [Indexed: 10/19/2022]
Abstract
The use of the highly effective Haemophilus influenzae type b (Hib) conjugate vaccine has increased globally. We review the benefits and limitations of studies measuring Hib vaccine effectiveness (VE). We critically examine the case-control approach by assessing the similarities and differences in methodology and findings and discuss the need for future Hib VE studies. In the absence of good surveillance data, vaccine effectiveness studies can play an important role, particularly with the increasing use of pneumococcal vaccine that has not been well tested under field conditions in less developed countries. However, the effectiveness of Hib vaccine has been well documented so the need for future VE Hib studies is minimal.
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Gessner BD, Adegbola RA. The impact of vaccines on pneumonia: key lessons from Haemophilus influenzae type b conjugate vaccines. Vaccine 2008; 26 Suppl 2:B3-8. [PMID: 18793604 DOI: 10.1016/j.vaccine.2008.04.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This article explores key lessons learned from vaccination with Haemophilus influenzae type b (Hib) conjugate vaccine and how these lessons may provide insight into the impact of emergent pneumococcal vaccines against pneumonia. The worldwide value of Hib vaccination for reducing Hib disease burden and carriage is reviewed. Using comparisons of data for pneumococcus versus Hib, the article concludes that epidemiological and biological differences between these pathogens will complicate efforts to use results from the Hib vaccine experience to predict outcomes following pneumococcal conjugate vaccine introduction.
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Affiliation(s)
- Bradford D Gessner
- Agence de Médecine Préventive, Institut Pasteur, 28 rue du Doctor Roux, F-75724 Paris, France.
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