Understanding the effectiveness of government interventions in Europe’s second wave of COVID-19

Abstract

As European governments face resurging waves of COVID-19, non-pharmaceutical interventions (NPIs) continue to be the primary tool for infection control. However, updated estimates of their relative effectiveness have been absent for Europe's second wave, largely due to a lack of collated data that considers the increased subnational variation and diversity of NPIs. We collect the largest dataset of NPI implementation dates in Europe, spanning 114 subnational areas in 7 countries, with a systematic categorisation of interventions tailored to the second wave. Using a hierarchical Bayesian transmission model, we estimate the effectiveness of 17 NPIs from local case and death data. We manually validate the data, address limitations in modelling from previous studies, and extensively test the robustness of our estimates. The combined effect of all NPIs was smaller relative to estimates from the first half of 2020, indicating the strong influence of safety measures and individual protective behaviours--such as distancing--that persisted after the first wave. Closing specific businesses was highly effective. Gathering restrictions were highly effective but only for the strictest limits. We find smaller effects for closing educational institutions compared to the first wave, suggesting that safer operation of schools was possible with a set of stringent safety measures including testing and tracing, preventing mixing, and smaller classes. These results underscore that effectiveness estimates from the early stage of an epidemic are measured relative to pre-pandemic behaviour. Updated estimates are required to inform policy in an ongoing pandemic.

Systematic review of empirical studies comparing the effectiveness of non-pharmaceutical interventions against COVID-19

“…In another preprint, Ge et al 99 analysed the effect of NPIs from the first wave until March 2021 in 133 countries, assessing vaccine rollouts as well. Consistent with Sharma et al 98 , Ge et al 99 observed differences in the effectiveness of NPIs during the different waves; they found that school closing was the most effective measure during the first wave, but not among the most relevant in the second. Gathering restrictions and facial covering requirements were consistently considered effective among waves, whereas international travel restrictions played a more important role in the control of the second wave.…”

“…However, several studies analysing the effectiveness of NPIs during the second wave have been released as preprints recently. Sharma et al 98 studied the implementation effects of 17 NPIs in 114 subnational areas from 7 European countries. They found that the combined effect of general NPI implementation was smaller during the second wave, which can be attributed, among other factors, to the influence of maintained individual protective behaviours after the first wave.…”

Mass mask-wearing notably reduces COVID-19 transmission

“…The Mask mandates are typically encoded as binary indicators that signal whether mask-wearing was required in at least some shared spaces [16,19,[29][30][31]. We draw mandate data from the OxCGRT NPI database [32].…”

“…Studying 41 countries, [18] infer an inconclusive mandate effect on COVID-19 transmission centred around zero. [19] is a regional study of 7 European countries [19] which finds an overall 7% to 17% (95% CI) reduction in transmission associated with mandates. In a mixed study of mask recommendations, mask mandates, cultural norms favouring masks, and self-reported wearing data, Leffler et al (2020) [16] find a 26% decrease in COVID-related mortality associated with their mixed proxy for mass mask-wearing.…”

“…The beginning of our window of analysis is determined by our datasets: the UMD project begins reporting in late April 2020 [7]. We end on the 1st September 2020, at the beginning of the second wave, a period in which national NPIs fragment into regional responses, making national analyses less informative [19].…”