The temporal association of introducing and lifting non-pharmaceutical interventions with the time-varying reproduction number (R) of SARS-CoV-2: a modelling study across 131 countries in The Lancet
DOI: 10.1016/S1473-3099(20)30785-4
In this study, we showed that closing schools alone could decrease transmission by 15% (R ratio 0·85, 95% CI 0·66–1·10) on day 28 and reopening schools could increase transmission by 24% (1·24, 1·00–1·52) on day 28
... as a single NPI, banning public events resulted in the greatest reduction in R, with an R ratio on day 28 of 0·76 (95% CI 0·58–1·00). This finding is unsurprising because a ban on crowded activities could prevent superspreading events, which were commonly reported at the beginning of the COVID-19 pandemic. Another explanation for the high reduction is that a ban on public events was often the first NPI to be introduced...
... lifting bans on gatherings of more than ten people could increase transmission by 25%, which was the highest increase among all NPIs. We did not observe a substantial reduction in transmission after introduction of bans on gatherings of more than ten or more than 100 people, especially for more than 100 people, which showed an increase in transmission after day 14; possible explanations for this finding include low adherence and, for the ban on gatherings of more than 100 people, an increase in smaller-scale gatherings.
