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Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate
BACKGROUND: In the ongoing Covid-19 pandemic, in the global data on the case fatality ratio (CFR) and other indices reflecting death rate, there is a consistent downward trend from mid-April to mid-November. The downward trend can be an illusion caused by biases and limitations of data or it could f...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
PeerJ Inc.
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8063871/ https://www.ncbi.nlm.nih.gov/pubmed/33976966 http://dx.doi.org/10.7717/peerj.11150 |
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author | Shinde, Sonali Ranade, Pratima Watve, Milind |
author_facet | Shinde, Sonali Ranade, Pratima Watve, Milind |
author_sort | Shinde, Sonali |
collection | PubMed |
description | BACKGROUND: In the ongoing Covid-19 pandemic, in the global data on the case fatality ratio (CFR) and other indices reflecting death rate, there is a consistent downward trend from mid-April to mid-November. The downward trend can be an illusion caused by biases and limitations of data or it could faithfully reflect a declining death rate. A variety of explanations for this trend are possible, but a systematic analysis of the testable predictions of the alternative hypotheses has not yet been attempted. METHODOLOGY: We state six testable alternative hypotheses, analyze their testable predictions using public domain data and evaluate their relative contributions to the downward trend. RESULTS: We show that a decline in the death rate is real; changing age structure of the infected population and evolution of the virus towards reduced virulence are the most supported hypotheses and together contribute to major part of the trend. The testable predictions from other explanations including altered testing efficiency, time lag, improved treatment protocols and herd immunity are not consistently supported, or do not appear to make a major contribution to this trend although they may influence some other patterns of the epidemic. CONCLUSION: The fatality of the infection showed a robust declining time trend between mid April to mid November. Changing age class of the infected and decreasing virulence of the pathogen were found to be the strongest contributors to the trend. |
format | Online Article Text |
id | pubmed-8063871 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | PeerJ Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-80638712021-05-10 Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate Shinde, Sonali Ranade, Pratima Watve, Milind PeerJ Epidemiology BACKGROUND: In the ongoing Covid-19 pandemic, in the global data on the case fatality ratio (CFR) and other indices reflecting death rate, there is a consistent downward trend from mid-April to mid-November. The downward trend can be an illusion caused by biases and limitations of data or it could faithfully reflect a declining death rate. A variety of explanations for this trend are possible, but a systematic analysis of the testable predictions of the alternative hypotheses has not yet been attempted. METHODOLOGY: We state six testable alternative hypotheses, analyze their testable predictions using public domain data and evaluate their relative contributions to the downward trend. RESULTS: We show that a decline in the death rate is real; changing age structure of the infected population and evolution of the virus towards reduced virulence are the most supported hypotheses and together contribute to major part of the trend. The testable predictions from other explanations including altered testing efficiency, time lag, improved treatment protocols and herd immunity are not consistently supported, or do not appear to make a major contribution to this trend although they may influence some other patterns of the epidemic. CONCLUSION: The fatality of the infection showed a robust declining time trend between mid April to mid November. Changing age class of the infected and decreasing virulence of the pathogen were found to be the strongest contributors to the trend. PeerJ Inc. 2021-04-20 /pmc/articles/PMC8063871/ /pubmed/33976966 http://dx.doi.org/10.7717/peerj.11150 Text en © 2021 Shinde et al. https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. |
spellingShingle | Epidemiology Shinde, Sonali Ranade, Pratima Watve, Milind Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate |
title | Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate |
title_full | Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate |
title_fullStr | Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate |
title_full_unstemmed | Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate |
title_short | Evaluating alternative hypotheses to explain the downward trend in the indices of the COVID-19 pandemic death rate |
title_sort | evaluating alternative hypotheses to explain the downward trend in the indices of the covid-19 pandemic death rate |
topic | Epidemiology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8063871/ https://www.ncbi.nlm.nih.gov/pubmed/33976966 http://dx.doi.org/10.7717/peerj.11150 |
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