Quantifying the impact of physical distance measures on the transmission of COVID-19 in the UK

By C. Jarvis, K. van Zandvoort, A. Gimma, Kiesha Prem, M. Auzenbergs, K. O’Reilly, G. Medley, J. Emery, R. Houben, Nicholas Davies and 28 more. BMC Medicine, 2020

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Background To mitigate and slow the spread of COVID-19, many countries have adopted unprecedented physical distancing policies, including the UK. We evaluate whether these measures might be sufficient to control the epidemic by estimating their impact on the reproduction number ( R 0 , the average number of secondary cases generated per case). Methods We asked a representative sample of UK adults about their contact patterns on the previous day. The questionnaire was conducted online via email recruitment and documents the age and location of contacts and a measure of their intimacy (whether physical contact was made or not). In addition, we asked about adherence to different physical distancing measures. The first surveys were sent on Tuesday, 24 March, 1 day after a “lockdown” was implemented across the UK. We compared measured contact patterns during the “lockdown” to patterns of social contact made during a non-epidemic period. By comparing these, we estimated the change in reproduction number as a consequence of the physical distancing measures imposed. We used a meta-analysis of published estimates to inform our estimates of the reproduction number before interventions were put in place. Results We found a 74% reduction in the average daily number of contacts observed per participant (from 10.8 to 2.8). This would be sufficient to reduce R 0 from 2.6 prior to lockdown to 0.62 (95% confidence interval [CI] 0.37–0.89) after the lockdown, based on all types of contact and 0.37 (95% CI = 0.22–0.53) for physical (skin to skin) contacts only. Conclusions The physical distancing measures adopted by the UK public have substantially reduced contact levels and will likely lead to a substantial impact and a decline in cases in the coming weeks. However, this projected decline in incidence will not occur immediately as there are significant delays between infection, the onset of symptomatic disease, and hospitalisation, as well as further delays to these events being reported. Tracking behavioural change can give a more rapid assessment of the impact of physical distancing measures than routine epidemiological surveillance.

Subfields: Clinical Psychology, Information Systems, Modeling and Simulation

View Paper: https://www.semanticscholar.org/paper/f67f8fbd6465aea380140c93db94878fa3488f4b

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In Modeling and Simulation

Citations in the corpus

Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England (2021, background): “031) 12 (11-12) 18 (18-18) 2a UK sequence separate-slopes binomial GLMM (1|LTLA/OBS) + REGION * DATE UK avg.”
Effects of non-pharmaceutical interventions on COVID-19 cases, deaths, and demand for hospital services in the UK: a modelling study (2020, neutral): “However, as a point of comparison, recent empirical estimates of the reproduction number in the UK 32,33 are compatible with our assumptions concerning R 0 and the impact of lockdown measures (appendix p 13) .”
Model-informed COVID-19 vaccine prioritization strategies by age and serostatus (2021, neutral): “We used pre-pandemic contact matrices (21), reflecting the goal of a return to pre-pandemic routines once a vaccine is available, but more recent estimates of age-stratified contact rates could be valuable in modeling mid-pandemic scenarios (36, 37).”
Non-pharmaceutical interventions during the COVID-19 pandemic: A review (2020, background): “similar study conducted during the lockdown in the UK report consistent, though smaller, reduction contacts (a factor ) [27].”