Settings for non-household transmission of SARS-CoV-2 during the second lockdown in England and Wales - analysis of the Virus Watch household community cohort study

Susan Hoskins; Sarah Beale; Vincent Nguyen; Ellen Fragaszy; Annalan M D Navaratnam; Colette Smith; Clare French; Jana Kovar; Thomas Byrne; Wing Lam Erica Fong; Cyril Geismar; Parth Patel; Alexei Yavlinksy; Anne M Johnson; Robert W Aldridge; Andrew Hayward; Virus Watch Collaborative

doi:10.12688/wellcomeopenres.17981.1

Settings for non-household transmission of SARS-CoV-2 during the second lockdown in England and Wales - analysis of the Virus Watch household community cohort study

Wellcome Open Res. 2022 Aug 3:7:199. doi: 10.12688/wellcomeopenres.17981.1. eCollection 2022.

Authors

Susan Hoskins¹, Sarah Beale^{1

2}, Vincent Nguyen^{1

2}, Ellen Fragaszy^{1

3}, Annalan M D Navaratnam^{1

2}, Colette Smith², Clare French⁴, Jana Kovar², Thomas Byrne¹, Wing Lam Erica Fong¹, Cyril Geismar^{1

2}, Parth Patel¹, Alexei Yavlinksy¹, Anne M Johnson⁵, Robert W Aldridge¹, Andrew Hayward²; Virus Watch Collaborative

Affiliations

¹ Centre for Public Health Data Science, Institute of Health Informatics, University College London, London, Greater London, WC1E 6BT, UK.
² Institute of Epidemiology and Healthcare, University College London, London, Greater London, WC1E 7HB, UK.
³ Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, Greater London, WC1E 7HT, UK.
⁴ NIHR Health Protection Research Unit in Behavioural Science and Evaluation, Uinversity of Bristol, Bristol, BS8 2BN, UK.
⁵ Institute for Global Health, University College London, London, WC1N 1EH, UK.

Abstract

Background: "Lockdowns" to control serious respiratory virus pandemics were widely used during the coronavirus disease 2019 (COVID-19) pandemic. However, there is limited information to understand the settings in which most transmission occurs during lockdowns, to support refinement of similar policies for future pandemics. Methods: Among Virus Watch household cohort participants we identified those infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outside the household. Using survey activity data, we undertook multivariable logistic regressions assessing the contribution of activities on non-household infection risk. We calculated adjusted population attributable fractions (APAF) to estimate which activity accounted for the greatest proportion of non-household infections during the pandemic's second wave. Results: Among 10,858 adults, 18% of cases were likely due to household transmission. Among 10,475 participants (household-acquired cases excluded), including 874 non-household-acquired infections, infection was associated with: leaving home for work or education (AOR 1.20 (1.02 - 1.42), APAF 6.9%); public transport (more than once per week AOR 1.82 (1.49 - 2.23), public transport APAF 12.42%); and shopping (more than once per week AOR 1.69 (1.29 - 2.21), shopping APAF 34.56%). Other non-household activities were rare and not significantly associated with infection. Conclusions: During lockdown, going to work and using public or shared transport independently increased infection risk, however only a minority did these activities. Most participants visited shops, accounting for one-third of non-household transmission. Transmission in restricted hospitality and leisure settings was minimal suggesting these restrictions were effective. If future respiratory infection pandemics emerge these findings highlight the value of working from home, using forms of transport that minimise exposure to others, minimising exposure to shops and restricting non-essential activities.

Keywords: Covid-19; SARS-CoV-2; activities; lockdown; pandemic; public transport; shopping; transmission; work.

Abstract

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