Abstract
In the absence of a vaccine, severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) transmission has been controlled by preventing person-to-person interactions via social distancing measures. In order to re-open parts of society, policy-makers need to consider how combinations of measures will affect transmission and understand the trade-offs between them. We use age-specific social contact data, together with epidemiological data, to quantify the components of the COVID-19 reproduction number. We estimate the impact of social distancing policies on the reproduction number by turning contacts on and off based on context and age. We focus on the impact of re-opening schools against a background of wider social distancing measures. We demonstrate that pre-collected social contact data can be used to provide a time-varying estimate of the reproduction number (R). We find that following lockdown (when R = 0.7, 95% CI 0.6, 0.8), opening primary schools has a modest impact on transmission (R = 0.89, 95% CI 0.82−0.97) as long as other social interactions are not increased. Opening secondary and primary schools is predicted to have a larger impact (R = 1.22, 95% CI 1.02−1.53). Contact tracing and COVID security can be used to mitigate the impact of increased social mixing to some extent; however, social distancing measures are still required to control transmission. Our approach has been widely used by policy-makers to project the impact of social distancing measures and assess the trade-offs between them. Effective social distancing, contact tracing and COVID security are required if all age groups are to return to school while controlling transmission.This article is part of the theme issue ‘Modelling that shaped the early COVID-19 pandemic response in the UK’.
Highlights
The reproduction number, or the ‘R number’, has become a central statistic used to characterize the transmission of severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2)
We find that if no other social contacts outside the home increase apart from those occurring within primary schools, re-opening primary schools is consistent with an R number less than 1, R 1⁄4 0:89 ð95% CI 0:82À0:97Þ
We present a method for mapping social distancing policies to an R number for COVID-19 using social contact data
Summary
The reproduction number, or the ‘R number’, has become a central statistic used to characterize the transmission of severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2). Surveys conducted in the UK during the COVID-19 pandemic have shown that social distancing dramatically decreased the average number of social interactions to less than three contacts per person per day [7]. Social distancing measures, such as the closure of schools and workplaces and the mandatory reduction of social interactions, while effective at preventing transmission, have severe economic and psychological effects, and of particular concern is their impact on children [8]. We use social contact data [5], including an additional targeted survey of children, to quantify the impact of re-opening schools on the R number in the UK [9]. For each of the Rt estimates, we calculate the mean and 95% confidence intervals for the R number by sampling contacts bootstrapping contacts, weighted by age, 2000 times and taking the percentile confidence interval
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