The potential contribution of face coverings to the control of SARS-CoV-2 transmission in schools and broader society in the UK: a modelling study

Abstract

Recent findings suggest that an adequate test-trace-isolate (TTI) strategy is needed to prevent a secondary COVID-19 wave with the reopening of society in the UK. Here we assess the potential importance of mandatory masks in the parts of community and in secondary schools. We show that, assuming current TTI levels, adoption of masks in secondary schools in addition to community settings can reduce the size of a second wave, but will not prevent it; more testing of symptomatic people, tracing and isolating of their contacts is also needed. To avoid a second wave, with masks mandatory in secondary schools and in certain community settings, under current tracing levels, 68% or 46% of those with symptomatic infection would need to be tested if masks' effective coverage were 15% or 30% respectively, compared to 76% and 57% if masks are mandated in community settings but not secondary schools.

Mathematical modeling as a tool for policy decision making: Applications to the COVID-19 pandemic

“…The methodology of the model is contained in Kerr et al (2020a) with further development and implementation details available at http://docs.covasim.org . Since the onset of the pandemic, Covasim has been applied across a number of studies ( Cohen et al, 2020 ; Kerr et al, 2020b ; Panovska-Griffiths et al, 2020 , Panovska-Griffits et al, 2020 ; Stuart et al, 2020 ). Here, we illustrate an application of Covasim to answer questions around the COVID-19 epidemic in the UK.…”

“…(C and D) Model predictions with increased social mixing and with reduced social mixing. Outcomes from an application of Covasim to the UK epidemic, calibrated to the reported COVID-19 infections and deaths until August 28, 2020 with model parameters as per ( Panovska-Griffits et al, 2020 ). Medians across 12 simulations are indicated by solid lines and 10% and 90% quantiles by shading.…”

“…To apply Covasim to the UK epidemic ( Panovska-Griffiths et al, 2020 , Panovska-Griffits et al, 2020 ), we used the default parameters and generated a population of 100,000 agents across the household, schools, workplaces and community networks. We then calibrated the model outcomes by performing an automated search for the optimal values of the number of infected people on 21 January 2020 (when the UK first COVID-19 case was confirmed), the per-contact transmission probability and the daily testing probabilities for individuals with and without COVID-19 symptoms during May, June, July, August and September (until September 26, 2020).…”

“…These particular parameters were selected as the most important to estimate because of the considerable uncertainties around them. Details of the exact methodology can be found in Kerr et al (2020a) and Panovska-Griffiths et al, 2020 , Panovska-Griffits et al, 2020 and the code used to run all simulations contained in here is available from https://github.com/Jasminapg/Covid-19-Analysis .…”

“…To simulate the impact of the masks policy, we defined effective coverage (a measure for effectiveness of masks) as the product of efficacy of masks (efficacy) and adherence to wearing them (coverage). A systematic review of the efficacy of face coverings suggested that taking in consideration different types of masks, their average efficacy is within the range of 11%–60% ( Panovska-Griffits et al, 2020b ). To simulate different face masks policy we then reduced the transmission probability of relevant contact network layers by the amount of effective coverage.…”