Effect of early application of social distancing interventions on COVID-19 mortality over the first pandemic wave: An analysis of longitudinal data from 37 countries

Objectives: To estimate the effect of early application of social distancing interventions on Covid-19 cumulative mortality during the first pandemic wave. Methods: Ecological longitudinal study using multivariable negative binomial regression for panel data. Daily numbers of Covid-19 cases and deaths, and data on social distancing interventions, for the 37 member countries of the Organization for Economic Cooperation and Development (OECD) were analysed. Results: Covid-19 cumulative mortality over the first pandemic wave varied widely across countries (range, 4.16 to 855 deaths per million population). On average, one-day delay in application of mass gatherings ban was associated with an adjusted increase in Covid-19 cumulative mortality by 6.97% (95% CI, 3.45 to 10.5), whilst a one-day delay in school closures was associated with an increase of 4.37% (95% CI, 1.58 to 7.17) over the study period. We estimated that if each country had enacted both interventions one week earlier, Covid-19 cumulative mortality could have been reduced by an average of 44.1% (95% CI, 20.2 to 67.9). Conclusions: Early application of mass gatherings ban and school closures in outbreak epicentres was associated with an important reduction in Covid-19 cumulative mortality during the first pandemic wave. These findings may support policy decision making. (C) 2020 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Automated summary

Early application of mass gatherings ban and school closures in outbreak epicentres was associated with a significant reduction in Covid-19 cumulative mortality during the first pandemic wave. If each country had implemented these two interventions one week earlier, Covid-19 cumulative mortality could have been reduced by an average of 44.1%.