Timing of the Winter Holiday and Excess Mortality Across Regions of Europe During the First Wave of the COVID-19 Pandemic – An Ecological Study

Abstract

Background: This ecological study of 219 regions in 11 European countries aimed to investigate the effect of the seemingly quasi-randomly assigned school winter holiday week on excess mortality associated with the COVID-19 pandemic during spring 2020. A secondary aim was to evaluate the impact of stringency and timing of the government responses to the early inflow of infected cases.Methods: Regional data on mortality week 14 – 23 in 2020 compared with the same period 2015 – 2019 were retrieved from Eurostat and national statistical agencies. Data on initial government responses were obtained from the Oxford COVID-19 Government Response Tracker. Variance-weighted least square regression was used to estimate the effect of winter holiday week and government responses with adjustment for population density and age distribution.Findings: Being a region with winter holiday exclusively in week 9 was in the adjusted analysis associated with 16 weekly excess deaths (95% CI 13 to 20) per million inhabitants, which corresponds to 38% of the excess mortality in these regions. A more stringent response implemented in week 11, corresponding to 10 additional units on the 0 – 100 ordinal scale, was associated with 20 fewer weekly deaths (95% CI 18 to 22) per million inhabitants.Interpretation: Winter holiday in week 9 was an amplifying event contributed importantly to the excess mortality observed in the study area during the spring 2020. Timely government response to the resulting early inflow of cases was associated with lower excess mortality.Funding: Swedish Research Council (Vetenskapsrådet; grant no. 2019 – 00198).Declaration of Interests: The authors declare no conflicting interests.Ethics Approval Statement: The authors stated that this study was entirely based on aggregated data so no ethical approval was necessary.