@article{98f1d3971b93425c95141ae48b4825d9,
title = "Changes in social contacts in England during the COVID-19 pandemic between March 2020 and March 2021 as measured by the CoMix survey: A repeated cross-sectional study",
abstract = "Background During: the Coronavirus Disease 2019 (CAU OVID-19): pandemic, the United Kingdom government imposed public health policies in England to reduce social contacts in hopes of curbing virus transmission. We conducted a repeated cross-sectional study to measure contact patterns weekly from March 2020 to March 2021 to estimate the impact of these policies, covering 3 national lockdowns interspersed by periods of less restrictive policies. Methods and findings The repeated cross-sectional survey data were collected using online surveys of representative samples of the UK population by age and gender. Survey participants were recruited by the online market research company Ipsos MORI through internet-based banner and social media ads and email campaigns. The participant data used for this analysis are restricted to those who reported living in England. We calculated the mean daily contacts reported using a (clustered) bootstrap and fitted a censored negative binomial model to estimate age-stratified contact matrices and estimate proportional changes to the basic reproduction number under controlled conditions using the change in contacts as a scaling factor. To put the findings in perspective, we discuss contact rates recorded throughout the year in terms of previously recorded rates from the POLYMOD study social contact study. The survey recorded 101,350 observations from 19,914 participants who reported 466,710 contacts over 53 weeks. We observed changes in social contact patterns in England over time and by participants{\textquoteright} age, personal risk factors, and perception of risk. The mean reported contacts for adults 18 to 59 years old ranged between 2.39 (95% confidence interval [CI] 2.20 to 2.60) contacts and 4.93 (95% CI 4.65 to 5.19) contacts during the study period. The mean contacts for school-age children (5 to 17 years old) ranged from 3.07 (95% CI 2.89 to 3.27) to 15.11 (95% CI 13.87 to 16.41). This demonstrates a sustained decrease in social contacts compared to a mean of 11.08 (95% CI 10.54 to 11.57) contacts per participant in all age groups combined as measured by the POLYMOD social contact study in 2005 to 2006. Contacts measured during periods of lockdowns were lower than in periods of eased social restrictions. The use of face coverings outside the home has remained high since the government mandated use in some settings in July 2020. The main limitations of this analysis are the potential for selection bias, as participants are recruited through internet-based campaigns, and recall bias, in which participants may under- or over-report the number of contacts they have made.",
author = "Amy Gimma and Munday, {James D.} and Wong, {Kerry L.M.} and Pietro Coletti and {van Zandvoort}, Kevin and Kiesha Prem and {CMMID COVID-19 Working Group} and Petra Klepac and Rubin, {G. James} and Sebastian Funk and Edmunds, {W. John} and Jarvis, {Christopher I.} and Chapman, {Lloyd A.C.} and Samuel Clifford and Thibaut Jombart and Kathleen O{\textquoteright}Reilly and Jiayao Lei and Kaja Abbas and Fabienne Krauer and Stefan Flasche and Alicia Rosello and Knight, {Gwenan M.} and Tully, {Damien C.} and Atkins, {Katherine E.} and Rachael Pung and Eggo, {Rosalind M.} and David Hodgson and Mihaly Koltai and Yalda Jafari and Russell, {Timothy W.} and Sandmann, {Frank G.} and Oliver Brady and Waterlow, {Naomi R.} and Mark Jit and Sun, {Fiona Yueqian} and Pearson, {Carl A.B.} and William Waites and Emilie Finch and Akira Endo and Graham Medley and McCarthy, {Ciara V.} and Kucharski, {Adam J.} and Paul Mee and Gibbs, {Hamish P.} and Davies, {Nicholas G.} and Quilty, {Billy J.} and Meakin, {Sophie R.} and Villabona-Arenas, {C. Julian} and Bosse, {Nikos I.} and Joel Hellewell and Procter, {Simon R.} and Yang Liu and Rachel Lowe and Barnard, {Rosanna C.} and Sam Abbott and Matthew Quaife and Nightingale, {Emily S.}",
note = "Funding Information: The following funding sources are acknowledged as providing funding for the named authors. This research was partly funded by the Bill & Melinda Gates Foundation (INV-003174: KP, PK). Elrha R2HC/UK FCDO/Wellcome Trust/This research was partly funded by the National Institute for Health Research (NIHR) using UK aid from the UK Government to support global health research. This project has received funding from the European Union{\textquoteright}s Horizon 2020 research and innovation programme - project EpiPose (101003688: AG, KP, PK, WJE). PC received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation program (Grant Agreement 682540 TransMID). FCDO/Wellcome Trust (Epidemic Preparedness Coronavirus research programme 221303/Z/20/Z: KvZ). This research was partly funded by the Global Challenges Research Fund (GCRF) project{\textquoteright}RECAP{\textquoteright} managed through RCUK and ESRC (ES/P010873/ 1: CIJ). NIHR (PR-OD-1017-20002: WJE). UK MRC (MC_PC_19065 - Covid 19: Understanding the dynamics and drivers of the COVID-19 epidemic using real-time outbreak analytics: WJE). Wellcome Trust (210758/Z/18/Z: JDM, SFunk). This research was partly funded by the Royal Society under award (RP\EA\180004: KP). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of Publisher Copyright: {\textcopyright} 2022 Gimma 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.",
year = "2022",
month = mar,
day = "1",
doi = "10.1371/journal.pmed.1003907",
language = "English",
volume = "19",
journal = "PLoS Medicine",
issn = "1549-1277",
publisher = "Public Library of Science",
number = "3",
}