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Brum AA, Duarte-Filho GC, Ospina R, Almeida FAG, Macêdo AMS, Vasconcelos GL. ModInterv: An automated online software for modeling epidemics. Softw Impacts 2022; 14:100409. [PMID: 35990010 PMCID: PMC9375249 DOI: 10.1016/j.simpa.2022.100409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/03/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
The COVID-19 pandemic has proven the importance of mathematical tools to understand the evolution of epidemic outbreaks and provide reliable information to the general public and health authorities. In this perspective, we have developed ModInterv, an online software that applies growth models to monitor the evolution of the COVID-19 epidemic in locations chosen by the user among countries worldwide or states and cities in the USA or Brazil. This paper describes the software capabilities and its use both in recent research works and by technical committees assisting government authorities. Possible applications to other epidemics are also briefly discussed.
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Affiliation(s)
- Arthur A Brum
- Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Gerson C Duarte-Filho
- Departamento de Física - Universidade Federal de Sergipe, 49100-000, São Cristóvão, Sergipe, Brazil
| | - Raydonal Ospina
- Departamento de Estatística, CASTLab, Universidade Federal de Pernambuco, 50740-540, Recife, Pernambuco, Brazil
| | - Francisco A G Almeida
- Departamento de Física - Universidade Federal de Sergipe, 49100-000, São Cristóvão, Sergipe, Brazil
| | - Antônio M S Macêdo
- Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Giovani L Vasconcelos
- Departamento de Física, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná, Brazil
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HERNÁNDEZ-RIVAS LUCÍA, FERNÁNDEZ-BRETON EVA, PEDRAZ TERESA, GARCÍA-VAZ CLAUDIA, CANTERO-ESCRIBANO JOSÉMIGUEL, MARTÍNEZ-CASTRO MERCEDES, PÉREZ-BLANCO VERÓNICA, ROBUSTILLORODELA ANA. First wave of the COVID-19 pandemic in Madrid: handling the unexpected in a tertiary hospital. J Prev Med Hyg 2022; 63:E375-E382. [PMID: 36415301 PMCID: PMC9648550 DOI: 10.15167/2421-4248/jpmh2022.63.3.2037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
INTRODUCTION The COVID-19 pandemic was declared on March 11th, 2020. By the end of January, the first imported cases were detected in Spain and, by March, the number of cases was growing exponentially, causing the implementation of a national lockdown. Madrid has been one of the most affected regions in terms of both cases and deaths. The aim of this study is to describe the epidemic curve and the epidemiological features and outcomes of COVID-19 patients hospitalized in La Paz University Hospital, a tertiary hospital located in Madrid. METHODS We included confirmed and probable COVID-19 cases admitted to our centre from February 26th to June 1st, 2020. We studied trends in hospitalization and ICU admissions using joinpoint regression analysis. RESULTS A sample of 2970 patients was obtained. Median age was 70 years old (IQR 55-82) and 54.8% of them were male. ICU admission rate was 8.7% with a mortality rate of 45.7%. Global CFR was 21.8%. Median time from symptom onset to death was 14 days (IQR 9-22). CONCLUSIONS We detected an admissions peak on March 21st followed by a descending trend, matching national and regional data. Age and sex distribution were comparable to further series nationally and in western countries.
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Affiliation(s)
- LUCÍA HERNÁNDEZ-RIVAS
- Correspondence: Lucía Hernández-Rivas, Department of Preventive Medicine, La Paz University Hospital, Madrid, Spain. E-mail:
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3
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Giraudo MT, Falcone M, Cislaghi C. [The wave train of COVID-19 infections]. Epidemiol Prev 2021; 45:580-587. [PMID: 35001600 DOI: 10.19191/ep21.6.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The present work studies the epidemic curve of COVID-19 in Italy between September 2020 and mid-June 2021 in terms of poussées, that is successive waves. There is obviously only one pandemic, although the virus has spread in the form of several variants, but the daily incidence trend can also be read in terms of overlapping of events that are different from each other or, in any case, induced by various phenomena. It can be hypothesized that in this way a succession of various waves was generated, which are modelled here using appropriate adaptation curves used in the study of epidemic data. Each curve corresponds approximately to the situation that would have occurred if no element had intervened to prevent the decrease of infections after the relative peak, while their overlap is considered to describe the subsequent increases. This interpolation has no predictive purpose, being purely descriptive over the time window under consideration. The discrepancies between the superposition of the modelling curves and the real epidemic curve are therefore also highlighted, especially in the transition periods between the various poussées. Finally, the analysis carried out allows to match the trend of the epidemic in the period considered with, on one hand, the series of events and, on the other, with the containment measures adopted which may have determined the succession of increases and decreases in the incidence of infections.
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Affiliation(s)
- Maria Teresa Giraudo
- Dipartimento di matematica "Giuseppe Peano", Università di Torino
- Gruppo AIE MADE
| | - Manuele Falcone
- Gruppo AIE MADE
- Azienda regionale di sanità della Toscana, Firenze
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Kolozsvári LR, Bérczes T, Hajdu A, Gesztelyi R, Tiba A, Varga I, Al-Tammemi AB, Szőllősi GJ, Harsányi S, Garbóczy S, Zsuga J. Predicting the epidemic curve of the coronavirus (SARS-CoV-2) disease (COVID-19) using artificial intelligence: An application on the first and second waves. Inform Med Unlocked 2021; 25:100691. [PMID: 34395821 PMCID: PMC8349399 DOI: 10.1016/j.imu.2021.100691] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/21/2021] [Accepted: 08/01/2021] [Indexed: 12/15/2022] Open
Abstract
Objectives The COVID-19 pandemic is considered a major threat to global public health. The aim of our study was to use the official epidemiological data to forecast the epidemic curves (daily new cases) of the COVID-19 using Artificial Intelligence (AI)-based Recurrent Neural Networks (RNNs), then to compare and validate the predicted models with the observed data. Methods We used publicly available datasets from the World Health Organization and Johns Hopkins University to create a training dataset, then we employed RNNs with gated recurring units (Long Short-Term Memory - LSTM units) to create two prediction models. Our proposed approach considers an ensemble-based system, which is realized by interconnecting several neural networks. To achieve the appropriate diversity, we froze some network layers that control the way how the model parameters are updated. In addition, we could provide country-specific predictions by transfer learning, and with extra feature injections from governmental constraints, better predictions in the longer term are achieved. We have calculated the Root Mean Squared Logarithmic Error (RMSLE), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE) to thoroughly compare our model predictions with the observed data. Results We reported the predicted curves for France, Germany, Hungary, Italy, Spain, the United Kingdom, and the United States of America. The result of our study underscores that the COVID-19 pandemic is a propagated source epidemic, therefore repeated peaks on the epidemic curve are to be anticipated. Besides, the errors between the predicted and validated data and trends seem to be low. Conclusion Our proposed model has shown satisfactory accuracy in predicting the new cases of COVID-19 in certain contexts. The influence of this pandemic is significant worldwide and has already impacted most life domains. Decision-makers must be aware, that even if strict public health measures are executed and sustained, future peaks of infections are possible. The AI-based models are useful tools for forecasting epidemics as these models can be recalculated according to the newly observed data to get a more precise forecasting.
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Affiliation(s)
- László Róbert Kolozsvári
- Department of Family and Occupational Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary
| | - Tamás Bérczes
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - András Hajdu
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - Rudolf Gesztelyi
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Tiba
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - Imre Varga
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - Ala'a B Al-Tammemi
- Department of Family and Occupational Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary
| | - Gergő József Szőllősi
- Department of Family and Occupational Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Szilvia Harsányi
- Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary.,Department of Health Systems Management and Quality Management in Health Care, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
| | - Szabolcs Garbóczy
- Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary.,Department of Psychiatry, Kenézy Hospital, University of Debrecen, Debrecen, Hungary
| | - Judit Zsuga
- Department of Health Systems Management and Quality Management in Health Care, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
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Kolozsvári LR, Bérczes T, Hajdu A, Gesztelyi R, Tiba A, Varga I, Al-Tammemi AB, Szőllősi GJ, Harsányi S, Garbóczy S, Zsuga J. Predicting the epidemic curve of the coronavirus (SARS-CoV-2) disease (COVID-19) using artificial intelligence: An application on the first and second waves. Inform Med Unlocked 2021; 25:100691. [PMID: 34395821 DOI: 10.1101/2020.04.17.20069666] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/21/2021] [Accepted: 08/01/2021] [Indexed: 05/27/2023] Open
Abstract
OBJECTIVES The COVID-19 pandemic is considered a major threat to global public health. The aim of our study was to use the official epidemiological data to forecast the epidemic curves (daily new cases) of the COVID-19 using Artificial Intelligence (AI)-based Recurrent Neural Networks (RNNs), then to compare and validate the predicted models with the observed data. METHODS We used publicly available datasets from the World Health Organization and Johns Hopkins University to create a training dataset, then we employed RNNs with gated recurring units (Long Short-Term Memory - LSTM units) to create two prediction models. Our proposed approach considers an ensemble-based system, which is realized by interconnecting several neural networks. To achieve the appropriate diversity, we froze some network layers that control the way how the model parameters are updated. In addition, we could provide country-specific predictions by transfer learning, and with extra feature injections from governmental constraints, better predictions in the longer term are achieved. We have calculated the Root Mean Squared Logarithmic Error (RMSLE), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE) to thoroughly compare our model predictions with the observed data. RESULTS We reported the predicted curves for France, Germany, Hungary, Italy, Spain, the United Kingdom, and the United States of America. The result of our study underscores that the COVID-19 pandemic is a propagated source epidemic, therefore repeated peaks on the epidemic curve are to be anticipated. Besides, the errors between the predicted and validated data and trends seem to be low. CONCLUSION Our proposed model has shown satisfactory accuracy in predicting the new cases of COVID-19 in certain contexts. The influence of this pandemic is significant worldwide and has already impacted most life domains. Decision-makers must be aware, that even if strict public health measures are executed and sustained, future peaks of infections are possible. The AI-based models are useful tools for forecasting epidemics as these models can be recalculated according to the newly observed data to get a more precise forecasting.
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Affiliation(s)
- László Róbert Kolozsvári
- Department of Family and Occupational Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary
| | - Tamás Bérczes
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - András Hajdu
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - Rudolf Gesztelyi
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Attila Tiba
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - Imre Varga
- Faculty of Informatics, University of Debrecen, Debrecen, Hungary
| | - Ala'a B Al-Tammemi
- Department of Family and Occupational Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary
| | - Gergő József Szőllősi
- Department of Family and Occupational Medicine, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Szilvia Harsányi
- Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary
- Department of Health Systems Management and Quality Management in Health Care, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
| | - Szabolcs Garbóczy
- Doctoral School of Health Sciences, University of Debrecen, Debrecen, Hungary
- Department of Psychiatry, Kenézy Hospital, University of Debrecen, Debrecen, Hungary
| | - Judit Zsuga
- Department of Health Systems Management and Quality Management in Health Care, Faculty of Public Health, University of Debrecen, Debrecen, Hungary
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Li M, Yuan Q, Chen P, Song B, Ma J. Estimating the quarantine failure rate for COVID-19. Infect Dis Model 2021; 6:924-929. [PMID: 34316527 PMCID: PMC8299156 DOI: 10.1016/j.idm.2021.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 11/29/2022] Open
Abstract
Quarantine is a crucial control measure in reducing imported COVID-19 cases and community transmissions. However, some quarantined COVID-19 patients may show symptoms after finishing quarantine due to a long median incubation period, potentially causing community transmissions. To assess the recommended 14-day quarantine policy, we develop a formula to estimate the quarantine failure rate from the incubation period distribution and the epidemic curve. We found that the quarantine failure rate increases with the exponential growth rate of the epidemic curve. We apply our formula to United States, Canada, and Hubei Province, China. Before the lockdown of Wuhan City, the quarantine failure rate in Hubei Province is about 4.1%. If the epidemic curve flattens or slowly decreases, the failure rate is less than 2.8%. The failure rate in US may be as high as 8.3%–11.5% due to a shorter 10-day quarantine period, while the failure rate in Canada may be between 2.5% and 3.9%. A 21-day quarantine period may reduce the failure rate to 0.3%–0.5%.
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Affiliation(s)
- Meili Li
- College of Science, Donghua University, Shanghai, 201620, China
| | - Qianqian Yuan
- College of Science, Donghua University, Shanghai, 201620, China
| | - Pian Chen
- College of Science, Donghua University, Shanghai, 201620, China
| | - Baojun Song
- Department of Applied Mathematics and Statistics, Montclair State University, Montclair, NJ, 07043, USA
| | - Junling Ma
- Department of Mathematics and Statistics, University of Victoria, Victoria, BC, V8W 2Y2, Canada
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Su SY, Lee WC. Monitoring the peaks of multiwave COVID-19 outbreaks. J Microbiol Immunol Infect 2021:S1684-1182(21)00144-4. [PMID: 34303622 DOI: 10.1016/j.jmii.2021.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 07/05/2021] [Accepted: 07/05/2021] [Indexed: 11/25/2022]
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Amani A, Tatang CA, Bayiha CN, Woung M, Ngo Bama S, Nangmo A, Mbang MA, Epee Douba E. A reactive vaccination campaign with single dose oral cholera vaccine (OCV) during a cholera outbreak in Cameroon. Vaccine 2021; 39:1290-6. [PMID: 33494966 DOI: 10.1016/j.vaccine.2021.01.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 11/16/2020] [Accepted: 01/04/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Cameroon chose Oral Cholera Vaccine (OCV) mass vaccination campaign in addition to other interventions to respond to outbreaks since 2015. There is still a persistent controversy on the effectiveness of reactive OCV mass vaccination campaign. OBJECTIVE This article aimed to share evidence-based observations on the effect of a reactive single-dose OCV mass vaccination campaign on cholera cases in Cameroon. METHODS Health area centered risk analysis was used to identify nine high risk health areas among four health districts in the |North Region as hotspots. About 537,274 people at risk of cholera transmission one year of age and above including pregnant women were eligible to receive OCV. A total of 537,279 doses of OCV was deployed for vaccination from August 1-5, 2019 through door-to-door strategy for urban health districts, and fixed/ temporary fixed posts strategies for rural health districts. RESULTS The overall vaccination coverage was 99.9%. Vaccine wastage rate was less than 0.5% (0.0011%). Independent monitoring showed vaccination coverage at 97.2%. The 2019 epidemic curve went down after OCV intervention on the contrary to that in the year 2018 at the same period. After OCV intervention, cholera cases dropped from about 10.5 to 9.3 cases per week at the regional level while at the district level, they dropped from 5.3 to 2.1, 2.2 to 1.7, 0.6 to 0 and 1.7 to 1.5 cases per week respectively for Garoua, Garoua II, Tchollire and Pitoa. Though not statistically significant (p = 1.4, α = 0.05), cases per 1000 population seemed to remain unchanged among OCV zones (0.32/1000) and non-OCV zones (0.31/1000) in 2018 while they increased from 0.37 (OCV zones) to 0.53 (non-0CV zones) cases per 1000 population in 2019. CONCLUSION There might have been a general trend in the reduction of the number of new cases after a reactive single-dose OCV campaign.
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Gonçalves L, Turkman MAA, Geraldes C, Marques TA, Sousa L. COVID-19: Nothing is Normal in this Pandemic. J Epidemiol Glob Health 2021; 11:146-149. [PMID: 33605119 PMCID: PMC8242106 DOI: 10.2991/jegh.k.210108.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 12/12/2020] [Indexed: 01/12/2023] Open
Abstract
This manuscript brings attention to inaccurate epidemiological concepts that emerged during the COVID-19 pandemic. In social media and scientific journals, some wrong references were given to a “normal epidemic curve” and also to a “log-normal curve/distribution”. For many years, textbooks and courses of reputable institutions and scientific journals have disseminated misleading concepts. For example, calling histogram to plots of epidemic curves or using epidemic data to introduce the concept of a Gaussian distribution, ignoring its temporal indexing. Although an epidemic curve may look like a Gaussian curve and be eventually modelled by a Gauss function, it is not a normal distribution or a log-normal, as some authors claim. A pandemic produces highly-complex data and to tackle it effectively statistical and mathematical modelling need to go beyond the “one-size-fits-all solution”. Classical textbooks need to be updated since pandemics happen and epidemiology needs to provide reliable information to policy recommendations and actions.
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Affiliation(s)
- Luzia Gonçalves
- Global Health and Tropical Medicine, Unidade de Saúde Pública Internacional e Bioestatística, Instituto de Higiene e Medicina Tropical, Universidade NOVA de Lisboa, Rua da Junqueira 100, Lisboa 1349-008, Portugal.,CEAUL - Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Portugal
| | | | - Carlos Geraldes
- CEAUL - Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Portugal.,ISEL - Instituto Superior de Engenharia de Lisboa - Instituto Politécnico de Lisboa, Portugal
| | - Tiago A Marques
- CEAUL - Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Portugal.,Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Portugal.,Centre for Research into Ecological and Environmental Modelling, The Observatory, University of St Andrews, Scotland
| | - Lisete Sousa
- CEAUL - Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Portugal.,Departamento de Estatística e Investigação Operacional, Faculdade de Ciências, Universidade de Lisboa, Portugal
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Abstract
A second wave of new severe acute respiratory syndrome coronavirus 2 (Covid-19) cases is widely feared. In fact resurgence of cases has been clearly observed in several countries that had seen flattening of the epidemic curve. In general, relaxation of community control measures is almost always blamed for the resurgence of cases. In this letter, the author describes an immunological explanation for the double-peaked epidemic curve of new viral diseases including Covid-19. According to this hypothesis, a second wave of cases is due to the effective innate immunity in some of the population. These individuals may later develop clinical disease upon repeated exposure. This theory claims that a double-peaked pattern of new cases in a new viral epidemic is intrinsically determined by the pattern of pathogen interaction with the host. According to this hypothesis, relaxation of the community control measures is not responsible; at least in part, for resurgence of cases.
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Affiliation(s)
- Osama Hussein
- Surgery Department, Mansoura University Oncology Center, Egypt.
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Perneger T, Kevorkian A, Grenet T, Gallée H, Gayet-Ageron A. Alternative graphical displays for the monitoring of epidemic outbreaks, with application to COVID-19 mortality. BMC Med Res Methodol 2020; 20:248. [PMID: 33023505 PMCID: PMC7537983 DOI: 10.1186/s12874-020-01122-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/15/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Classic epidemic curves - counts of daily events or cumulative events over time -emphasise temporal changes in the growth or size of epidemic outbreaks. Like any graph, these curves have limitations: they are impractical for comparisons of large and small outbreaks or of asynchronous outbreaks, and they do not display the relative growth rate of the epidemic. Our aim was to propose two additional graphical displays for the monitoring of epidemic outbreaks that overcome these limitations. METHODS The first graph shows the growth of the epidemic as a function of its size; specifically, the logarithm of new cases on a given day, N(t), is plotted against the logarithm of cumulative cases C(t). Logarithm transformations facilitate comparisons of outbreaks of different sizes, and the lack of a time scale overcomes the need to establish a starting time for each outbreak. Notably, on this graph, exponential growth corresponds to a straight line with a slope equal to one. The second graph represents the logarithm of the relative rate of growth of the epidemic over time; specifically, log10(N(t)/C(t-1)) is plotted against time (t) since the 25th event. We applied these methods to daily death counts attributed to COVID-19 in selected countries, reported up to June 5, 2020. RESULTS In most countries, the log(N) over log(C) plots showed initially a near-linear increase in COVID-19 deaths, followed by a sharp downturn. They enabled comparisons of small and large outbreaks (e.g., Switzerland vs UK), and identified outbreaks that were still growing at near-exponential rates (e.g., Brazil or India). The plots of log10(N(t)/C(t-1)) over time showed a near-linear decrease (on a log scale) of the relative growth rate of most COVID-19 epidemics, and identified countries in which this decrease failed to set in in the early weeks (e.g., USA) or abated late in the outbreak (e.g., Portugal or Russia). CONCLUSIONS The plot of log(N) over log(C) displays simultaneously the growth and size of an epidemic, and allows easy identification of exponential growth. The plot of the logarithm of the relative growth rate over time highlights an essential parameter of epidemic outbreaks.
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Affiliation(s)
- Thomas Perneger
- Division of clinical epidemiology, Geneva University Hospitals, and Faculty of medicine, University of Geneva, Geneva, Switzerland.
| | | | - Thierry Grenet
- Neel Institute, Université Grenoble Alpes, Grenoble, France
| | - Hubert Gallée
- Institute of Environmental Geosciences, Université Grenoble Alpes, Grenoble, France
| | - Angèle Gayet-Ageron
- Division of clinical epidemiology, Geneva University Hospitals, and Faculty of medicine, University of Geneva, Geneva, Switzerland
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Păcurar CM, Necula BR. An analysis of COVID-19 spread based on fractal interpolation and fractal dimension. Chaos Solitons Fractals 2020; 139:110073. [PMID: 32834617 PMCID: PMC7332948 DOI: 10.1016/j.chaos.2020.110073] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/23/2020] [Accepted: 07/01/2020] [Indexed: 05/04/2023]
Abstract
The present paper proposes a reconstruction of the epidemic curves from the fractal interpolation point of view. Looking at the epidemic curves as fractal structures might be an efficient way to retrieve missing pieces of information due to insufficient testing and predict the evolution of the disease. A fractal approach of the epidemic curve can contribute to the assessment and modeling of other epidemics. On the other hand, we have considered the spread of the epidemic in countries like Romania, Italy, Spain, and Germany and analyzed the spread of the disease in those countries based on their fractal dimension.
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Affiliation(s)
- Cristina-Maria Păcurar
- Faculty of Mathematics and Informatics, Transilvania University of Braşov, Bulevardul Eroilor 29, Braşov 500036, Romania
| | - Bogdan-Radu Necula
- Faculty of Medicine, Transilvania University of Braşov, Bulevardul Eroilor 29, Braşov 500036, Romania
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Chen T, Guo S, Zhong P. Epidemic characteristics of the COVID-19 outbreak in Tianjin, a well-developed city in China. Am J Infect Control 2020; 48:1068-1073. [PMID: 32540369 PMCID: PMC7291981 DOI: 10.1016/j.ajic.2020.06.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/08/2020] [Accepted: 06/08/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND Coronavirus disease 2019 (COVID-19) is already a pandemic. Few studies investigated the epidemic characteristics of the COVID-19 outbreak in the well-developed cities. METHODS Epidemiological data of 136 confirmed COVID-19 cases were collected from the dataset of COVID-19 in Tianjin. All confirmed cases were categorized according to their potential infection sources. Daily numbers of confirmed cases of each category were plotted by date of onset, and the epidemic form of each category was inferred. RESULTS Among the 136 confirmed COVID-19 cases, 48 cases were categorized as imported cases and their close contacts, which were the majority of early cases. A total of 43 cases were found an epidemiological link to the Baodi department store, and they were inferred to be a common-source outbreak. Additionally, 35 cases were considered as familial clusters of COVID-19 cases, and 10 cases were sporadic. The 45 cases were inferred to be a propagated epidemic. CONCLUSIONS Local transmission of COVID-19 mainly occurred within families and a poorly ventilated public place in Tianjin. Besides the imported cases, the pattern of local transmission of COVID-19 was a mixture of the propagated epidemic and the common-source outbreak in Tianjin.
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Affiliation(s)
- Ting Chen
- Department of Medical Examination and Blood Donation, Xiamen Blood Center (Xiamen Central Blood Station), Xiamen, China
| | - Songxue Guo
- Department of Plastic Surgery, The Second Affiliated Hospital Zhejiang University School of Medicine, Hangzhou, China
| | - Ping Zhong
- BE and Phase I Clinical Trial Center, The First Affiliated Hospital of Xiamen University, Xiamen, China.
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Chattu VK, Adisesh A, Yaya S. Canada's role in strengthening global health security during the COVID-19 pandemic. Glob Health Res Policy 2020; 5:16. [PMID: 32328533 PMCID: PMC7167363 DOI: 10.1186/s41256-020-00146-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/13/2020] [Indexed: 12/05/2022] Open
Abstract
The world is confronted by the current pandemic of Corona Virus Disease (COVID-19), which is a wake-up call for all nations irrespective of their development status or geographical location. Since the start of the century we have seen five big infectious outbreaks which proved that epidemics are no more regarded as historic and geographically confined threats. The Canadian government underlined that these infectious disease outbreaks are threats to global health security and disrupt societal wellbeing and development. In this context, the Public Health Agency of Canada is proactive and has shown its preparedness for outbreaks of emerging and epidemic-prone diseases, and in dealing with these pathogens. Even before the declaration of pandemic, Canada has proved its global health leadership by ensuring collective action and multisectoral coordination which still remains a serious challenge especially for low and middle- income countries with existing poor health systems. In this article we discuss how Canada is addressing the global challenges posed by the COVID-19 pandemic through its leadership and practice of global health diplomacy.
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Affiliation(s)
- Vijay Kumar Chattu
- 1Division of Occupational Medicine, Department of Medicine, University of Toronto, Toronto, ON Canada.,2Occupational Medicine Clinic, St. Michael's Hospital, Unity Health Toronto, Toronto, ON Canada.,3Institute of International Relations, The University of the West Indies, St. Augustine, Trinidad and Tobago
| | - Anil Adisesh
- 1Division of Occupational Medicine, Department of Medicine, University of Toronto, Toronto, ON Canada.,2Occupational Medicine Clinic, St. Michael's Hospital, Unity Health Toronto, Toronto, ON Canada
| | - Sanni Yaya
- 4School of International Development and Global Studies, Faculty of Social Sciences, University of Ottawa, Ottawa, ON Canada.,5The George Institute for Global Health, University of Oxford, Oxford, UK
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15
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Abstract
The initial exponential growth rate of an epidemic is an important measure of the severeness of the epidemic, and is also closely related to the basic reproduction number. Estimating the growth rate from the epidemic curve can be a challenge, because of its decays with time. For fast epidemics, the estimation is subject to over-fitting due to the limited number of data points available, which also limits our choice of models for the epidemic curve. We discuss the estimation of the growth rate using maximum likelihood method and simple models.
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Affiliation(s)
- Junling Ma
- Department of Mathematics and Statistics, University of Victoria, Victoria, BC, V8W 2Y2, Canada
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16
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Nakamura T, Maruyama A, Misaki T, Okabe N, Shinmei K, Hashizume M, Murakami Y, Nishiwaki Y. [Evaluation of real-time surveillance of influenza incidence in Kawasaki City by comparison using the National Epidemiological Surveillance of Infectious Diseases]. Nihon Koshu Eisei Zasshi 2019; 65:666-676. [PMID: 30518705 DOI: 10.11236/jph.65.11_666] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Objectives In Japan, nationwide data of the incidence of infectious diseases have been collected via the National Epidemiological Surveillance of Infectious Diseases (NESID) since 1981. In addition, since March 2014, Kawasaki City has operated its own real-time surveillance (RTS) system to collect data of the incidence of influenza from medical institutions across the city. This study aimed to describe the characteristics of the RTS system and compare the two surveillance systems to improve measures against infectious diseases in the future.Methods NESID and RTS data from March 2014 to October 2017 were obtained from the Kawasaki City Institute for Public Health. First, the operating methodologies of the two surveillance systems were compared. Second, RTS data were used to analyze the daily epidemic curve, and then the daily number of influenza cases was converted into weekly data for comparison with NESID data. Pearson's correlation coefficients and 95% confidence intervals (CIs) were calculated. Correlations were also analyzed after data for the last and first weeks of each year were excluded because few hospitals remain open around the New Year holiday, resulting in a disproportionately large number of patients visiting the few institutions that remain open.Results The NESID relies on data provided by a fixed number of medical institutions determined each fiscal year (mean: 56.0±4.2 institutions), while the number of institutions providing data for the RTS varies daily or monthly. In September 2017, 691 of the 1,032 eligible institutions (67.0%) were registered for the RTS. Pearson's correlation coefficient for the two surveillance systems was 0.975 (95%CI, 0.967-0.981); when data for the last and first week of each year were excluded, it was 0.989 (95%CI 0.986-0.992). In each of the three seasons that were investigated, an increase in the incidence of type A influenza preceded an increase in the incidence of type B influenza.Conclusion The operating methodologies of the two surveillance systems differed; however, the results identified a strong correlation, confirming the reliability of the RTS. The RTS collects daily data by influenza type; therefore, it detects epidemic onsets at an earlier stage, facilitating more detailed epidemiological analysis, compared with that of the NESID. It is necessary to understand differences in the characteristics between two surveillance systems when we analyze influenza surveillance data.
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Affiliation(s)
- Takahiro Nakamura
- Department of Environmental and Occupational Health, School of Medicine, Toho University, Tokyo, Japan
| | | | | | | | - Keita Shinmei
- Department of Environmental and Occupational Health, School of Medicine, Toho University, Tokyo, Japan.,Department of Preventive Medicine and Public Health, School of Medicine, Keio University, Tokyo, Japan
| | - Masahiro Hashizume
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Yoshitaka Murakami
- Department of Medical Statistics, School of Medicine, Toho University, Tokyo, Japan
| | - Yuji Nishiwaki
- Department of Environmental and Occupational Health, School of Medicine, Toho University, Tokyo, Japan
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Svensson Å. The influence of assumptions on generation time distributions in epidemic models. Math Biosci 2015; 270:81-9. [PMID: 26477379 DOI: 10.1016/j.mbs.2015.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/07/2015] [Accepted: 10/08/2015] [Indexed: 10/22/2022]
Abstract
A simple class of stochastic models for epidemic spread in finite, but large, populations is studied. The purpose is to investigate how assumptions about the times between primary and secondary infections influences the outcome of the epidemic. Of particular interest is how assumptions of individual variability in infectiousness relates to variability of the epidemic curve. The main concern is the final size of the epidemic and the time scale at which it evolves. The theoretical results are illustrated by simulations.
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Affiliation(s)
- Åke Svensson
- Department of Mathematics, Stockholm university, SE-106 91 Stockholm, Sweden.
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18
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Furuya H. Estimation of reproduction number and probable vector density of the first autochthonous dengue outbreak in Japan in the last 70 years. Environ Health Prev Med 2015; 20:466-71. [PMID: 26298188 DOI: 10.1007/s12199-015-0488-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 08/05/2015] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES The first autochthonous case of dengue fever in Japan since 1945 was reported on August 27, 2014. Infection was transmitted by Aedes albopictus mosquitoes in Tokyo's Yoyogi Park. A total of 65 cases with no history of overseas travel and who may have been infected around the park were reported as of September 5, 2014. To quantify infection risk of the local epidemic, the reproduction number and vector density per person at the onset of the epidemic were estimated. METHODS The estimated probability distribution and the number of female mosquitoes per person (MPP) were determined from the data of the initial epidemic. RESULTS The estimated distribution R(0i) for the initial epidemic was fitted to a Gamma distribution using location parameter 4.25, scale parameter 0.19, and shape parameter 7.76 with median 7.78 and IQR (7.21-8.40). The MPP was fitted to a normal distribution with mean 5.71 and standard deviation 0.53. CONCLUSIONS Both estimated reproduction number and vector density per person at the onset of the epidemic were higher than previously reported values. These results indicate the potential for dengue outbreaks in places with elevated vector density per person, even in dengue non-endemic countries. To investigate the cause of this outbreak, further studies will be needed, including assessments of social, behavioral, and environmental factors that may have contributed to this epidemic by altering host and vector conditions in the park.
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Affiliation(s)
- Hiroyuki Furuya
- Basic Clinical Science and Public Health, Tokai University School of Medicine, 143 Shimokasuya, Isehara-shi, Kanagawa, 259-1193, Japan.
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