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Gomes MGM, Ferreira MU, Corder RM, King JG, Souto-Maior C, Penha-Gonçalves C, Gonçalves G, Chikina M, Pegden W, Aguas R. Individual variation in susceptibility or exposure to SARS-CoV-2 lowers the herd immunity threshold. J Theor Biol 2022; 540:111063. [PMID: 35189135 PMCID: PMC8855661 DOI: 10.1016/j.jtbi.2022.111063] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 02/14/2022] [Accepted: 02/15/2022] [Indexed: 12/21/2022]
Abstract
Individual variation in susceptibility and exposure is subject to selection by natural infection, accelerating the acquisition of immunity, and reducing herd immunity thresholds and epidemic final sizes. This is a manifestation of a wider population phenomenon known as "frailty variation". Despite theoretical understanding, public health policies continue to be guided by mathematical models that leave out considerable variation and as a result inflate projected disease burdens and overestimate the impact of interventions. Here we focus on trajectories of the coronavirus disease (COVID-19) pandemic in England and Scotland until November 2021. We fit models to series of daily deaths and infer relevant epidemiological parameters, including coefficients of variation and effects of non-pharmaceutical interventions which we find in agreement with independent empirical estimates based on contact surveys. Our estimates are robust to whether the analysed data series encompass one or two pandemic waves and enable projections compatible with subsequent dynamics. We conclude that vaccination programmes may have contributed modestly to the acquisition of herd immunity in populations with high levels of pre-existing naturally acquired immunity, while being crucial to protect vulnerable individuals from severe outcomes as the virus becomes endemic.
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Affiliation(s)
- M Gabriela M Gomes
- Department of Mathematics and Statistics, University of Strathclyde, Glasgow, UK; Centro de Matemática e Aplicações, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Marcelo U Ferreira
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Nova University of Lisbon, Lisbon, Portugal
| | - Rodrigo M Corder
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Jessica G King
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | - Caetano Souto-Maior
- Laboratory of Systems Genetics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | | | - Guilherme Gonçalves
- Unidade Multidisciplinar de Investigação Biomédica, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria Chikina
- Department of Computational and Systems Biology, University of Pittsburgh, Pittburgh, PA, USA
| | - Wesley Pegden
- Department of Mathematical Sciences, Carnegie Mellon University, Pittburgh, PA, USA
| | - Ricardo Aguas
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Gomes MGM, Ferreira MU, Corder RM, King JG, Souto-Maior C, Penha-Gonçalves C, Gonçalves G, Chikina M, Pegden W, Aguas R. Individual variation in susceptibility or exposure to SARS-CoV-2 lowers the herd immunity threshold. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2022:2020.04.27.20081893. [PMID: 32511451 PMCID: PMC7239079 DOI: 10.1101/2020.04.27.20081893] [Citation(s) in RCA: 128] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Individual variation in susceptibility and exposure is subject to selection by natural infection, accelerating the acquisition of immunity, and reducing herd immunity thresholds and epidemic final sizes. This is a manifestation of a wider population phenomenon known as "frailty variation". Despite theoretical understanding, public health policies continue to be guided by mathematical models that leave out considerable variation and as a result inflate projected disease burdens and overestimate the impact of interventions. Here we focus on trajectories of the coronavirus disease (COVID-19) pandemic in England and Scotland until November 2021. We fit models to series of daily deaths and infer relevant epidemiological parameters, including coefficients of variation and effects of non-pharmaceutical interventions which we find in agreement with independent empirical estimates based on contact surveys. Our estimates are robust to whether the analysed data series encompass one or two pandemic waves and enable projections compatible with subsequent dynamics. We conclude that vaccination programmes may have contributed modestly to the acquisition of herd immunity in populations with high levels of pre-existing naturally acquired immunity, while being critical to protect vulnerable individuals from severe outcomes as the virus becomes endemic.
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Affiliation(s)
- M Gabriela M Gomes
- Department of Mathematics and Statistics, University of Strathclyde, Glasgow, UK
- Centro de Matemática e Aplicações, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Marcelo U Ferreira
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Nova University of Lisbon, Lisbon, Portugal
| | - Rodrigo M Corder
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Jessica G King
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | - Caetano Souto-Maior
- Laboratory of Systems Genetics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | | | - Guilherme Gonçalves
- Unidade Multidisciplinar de Investigação Biomédica, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Maria Chikina
- Department of Computational and Systems Biology, University of Pittsburgh, Pittburgh, PA, USA
| | - Wesley Pegden
- Department of Mathematical Sciences, Carnegie Mellon University, , Pittburgh" , PA, USA
| | - Ricardo Aguas
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Stump SM, Song C, Saavedra S, Levine JM, Vasseur DA. Synthesizing the effects of individual‐level variation on coexistence. ECOL MONOGR 2021. [DOI: 10.1002/ecm.1493] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Simon Maccracken Stump
- Department of Ecology & Evolutionary Biology Yale University New Haven Connecticut 06511 USA
| | - Chuliang Song
- Department of Civil and Environmental Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA
| | - Serguei Saavedra
- Department of Civil and Environmental Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA
| | - Jonathan M. Levine
- Department of Ecology & Evolutionary Biology Princeton University Princeton New Jersey 08544 USA
| | - David A. Vasseur
- Department of Ecology & Evolutionary Biology Yale University New Haven Connecticut 06511 USA
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