The impact of contact tracing and household bubbles on deconfinement strategies for COVID-19

Sereina A Herzog,Philippe Beutels,Christel Faes,Elise Kuylen,Pieter J K Libin,James Wambua,Oana Petrof,Niel Hens,Pietro Coletti,Steven Abrams,Signe Møgelmose,Lander Willem

doi:10.1038/s41467-021-21747-7

Abstract

The COVID-19 pandemic caused many governments to impose policies restricting social interactions. A controlled and persistent release of lockdown measures covers many potential strategies and is subject to extensive scenario analyses. Here, we use an individual-based model (STRIDE) to simulate interactions between 11 million inhabitants of Belgium at different levels including extended household settings, i.e., “household bubbles”. The burden of COVID-19 is impacted by both the intensity and frequency of physical contacts, and therefore, household bubbles have the potential to reduce hospital admissions by 90%. In addition, we find that it is crucial to complete contact tracing 4 days after symptom onset. Assumptions on the susceptibility of children affect the impact of school reopening, though we find that business and leisure-related social mixing patterns have more impact on COVID-19 associated disease burden. An optimal deployment of the mitigation policies under study require timely compliance to physical distancing, testing and self-isolation.

Highlights

The COVID-19 pandemic caused many governments to impose policies restricting social interactions
Social contact patterns can be used as a proxy for transmission dynamics when relying on the “social contact hypothesis”[7]
We calibrated the transmission model up to April 30th, 2020, and continued all simulations up to August 31st to assess the impact of different deconfinement strategies

Summary

Introduction

The COVID-19 pandemic caused many governments to impose policies restricting social interactions. The burden of COVID-19 is impacted by both the intensity and frequency of physical contacts, and household bubbles have the potential to reduce hospital admissions by 90%. Releasing society’s lockdown while keeping the spread of the virus under control, requires detailed models to simulate the (non-) propagation of SARS-Cov-2. To this end, it is important to capture the heterogeneity in social encounters by accounting for a low number of intense contacts (e.g., between household members) and a high(er) number of more fleeting contacts (e.g., during leisure activities, commuting, or in shops)[1]. Social contact patterns in a transmission model can be adjusted to simulate behavioural change and assess possible intervention strategies[4]. Given the rising number of confirmed COVID-19 cases and hospital admissions in Belgium during the beginning of March

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Conclusion