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Estimating the effects of lockdown timing on COVID-19 cases and deaths in England: a counterfactual modelling study

Estimating the effects of lockdown timing on COVID-19 cases and deaths in England: a counterfactual modelling study
Estimating the effects of lockdown timing on COVID-19 cases and deaths in England: a counterfactual modelling study
Background: during the first wave of the COVID-19 pandemic, the United Kingdom experienced one of the highest per-capita death tolls worldwide. It is debated whether this may partly be explained by the relatively late initiation of voluntary social distancing and mandatory lockdown measures. In this study, we used simulations to estimate the number of cases and deaths that would have occurred in England by 1 June 2020 if these interventions had been implemented one or two weeks earlier, and the impact on the required duration of lockdown.

Methods: using official reported data on the number of Pillar 1 lab-confirmed cases of COVID-19 and associated deaths occurring in England from 3 March to 1 June, we modelled: the natural (i.e. observed) growth of cases, and the counterfactual (i.e. hypothetical) growth of cases that would have occurred had measures been implemented one or two weeks earlier. Under each counterfactual condition, we estimated the expected number of deaths and the time required to reach the incidence observed under natural growth on 1 June.

Results: introducing measures one week earlier would have reduced by 74% the number of confirmed COVID-19 cases in England by 1 June, resulting in approximately 21,000 fewer hospital deaths and 34,000 fewer total deaths; the required time spent in full lockdown could also have been halved, from 69 to 35 days. Acting two weeks earlier would have reduced cases by 93%, resulting in between 26,000 and 43,000 fewer deaths.

Conclusions: our modelling supports the claim that the relatively late introduction of social distancing and lockdown measures likely increased the scale, severity, and duration of the first wave of COVID-19 in England. Our results highlight the importance of acting swiftly to minimise the spread of an infectious disease when case numbers are increasing exponentially.
1932-6203
Arnold, Kellyn F.
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Gilthorpe, Mark S.
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Alwan, Nisreen
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Heppenstall, Alison J.
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Tomova, Georgia D.
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McKee, Martin
6d38c3d0-0235-4d79-83c2-1499fd872b28
Tennant, Peter W.G.
a9c3f730-540a-4c08-98b0-bbc027381dec
Arnold, Kellyn F.
86c665cd-492b-4d3b-b998-2cfd37da18f2
Gilthorpe, Mark S.
8c9fed51-5f16-43bb-8097-250483b80a5c
Alwan, Nisreen
0d37b320-f325-4ed3-ba51-0fe2866d5382
Heppenstall, Alison J.
0579dabe-2512-47d6-b079-0eb93ad81985
Tomova, Georgia D.
4a2b1571-e462-46ad-9760-2dc2224d838e
McKee, Martin
6d38c3d0-0235-4d79-83c2-1499fd872b28
Tennant, Peter W.G.
a9c3f730-540a-4c08-98b0-bbc027381dec

Arnold, Kellyn F., Gilthorpe, Mark S., Alwan, Nisreen, Heppenstall, Alison J., Tomova, Georgia D., McKee, Martin and Tennant, Peter W.G. (2022) Estimating the effects of lockdown timing on COVID-19 cases and deaths in England: a counterfactual modelling study. PLoS ONE, 17 (4 April), [e0263432]. (doi:10.1371/journal.pone.0263432).

Record type: Article

Abstract

Background: during the first wave of the COVID-19 pandemic, the United Kingdom experienced one of the highest per-capita death tolls worldwide. It is debated whether this may partly be explained by the relatively late initiation of voluntary social distancing and mandatory lockdown measures. In this study, we used simulations to estimate the number of cases and deaths that would have occurred in England by 1 June 2020 if these interventions had been implemented one or two weeks earlier, and the impact on the required duration of lockdown.

Methods: using official reported data on the number of Pillar 1 lab-confirmed cases of COVID-19 and associated deaths occurring in England from 3 March to 1 June, we modelled: the natural (i.e. observed) growth of cases, and the counterfactual (i.e. hypothetical) growth of cases that would have occurred had measures been implemented one or two weeks earlier. Under each counterfactual condition, we estimated the expected number of deaths and the time required to reach the incidence observed under natural growth on 1 June.

Results: introducing measures one week earlier would have reduced by 74% the number of confirmed COVID-19 cases in England by 1 June, resulting in approximately 21,000 fewer hospital deaths and 34,000 fewer total deaths; the required time spent in full lockdown could also have been halved, from 69 to 35 days. Acting two weeks earlier would have reduced cases by 93%, resulting in between 26,000 and 43,000 fewer deaths.

Conclusions: our modelling supports the claim that the relatively late introduction of social distancing and lockdown measures likely increased the scale, severity, and duration of the first wave of COVID-19 in England. Our results highlight the importance of acting swiftly to minimise the spread of an infectious disease when case numbers are increasing exponentially.

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Accepted/In Press date: 19 January 2022
Published date: 14 April 2022
Additional Information: Funding Information: KFA, MSG, GDT, and PWGT were supported by The Alan Turing Institute [grant number EP/N510129/1, https://www.turing.ac.uk]. The Alan Turing Institute has no in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Publisher Copyright: Copyright: © 2022 Arnold et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Identifiers

Local EPrints ID: 454579
URI: http://eprints.soton.ac.uk/id/eprint/454579
ISSN: 1932-6203
PURE UUID: 8169e540-6465-4baf-ba17-26372f2641a6
ORCID for Nisreen Alwan: ORCID iD orcid.org/0000-0002-4134-8463

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Date deposited: 16 Feb 2022 17:43
Last modified: 17 Mar 2024 03:38

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Contributors

Author: Kellyn F. Arnold
Author: Mark S. Gilthorpe
Author: Nisreen Alwan ORCID iD
Author: Alison J. Heppenstall
Author: Georgia D. Tomova
Author: Martin McKee
Author: Peter W.G. Tennant

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