Excess mortality across regions of Europe during the first wave of the COVID-19 pandemic – impact of the winter holiday travelling and government responses

Abstract

BackgroundThis aggregated population study of 219 regions in 11 European countries investigated 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.MethodsRegional 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 with further adjustment for population density and age distribution.ResultsBeing a region with winter holiday exclusively in week 9 was in the adjusted analysis associated with 16 weekly excess deaths (95% confidence interval 13 to 20) per million inhabitants, which corresponds to 38% of the excess mortality during the study period 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% confidence interval 18 to 22) per million inhabitants.ConclusionsTravelling during winter holiday in week 9 was an amplifying event that contributed importantly to the excess mortality observed in the study area during the spring 2020. Timely government responses to the resulting early inflow of cases was associated with lower excess mortality.

Do school closures and school reopenings affect community transmission of COVID-19? A systematic review of observational studies

“…Included studies are described in Table 1, grouped by exposure type and study design. Of these, 32 studies(14,15,18–21,23,24,26,29–40,42–44,46–53) reported the effect of school closures on community transmission of SARS-CoV-2, 11(16,22–25,27,28,35,43–45) examined school reopening, and 3(16,17,41) investigated the effect of school holidays. Some studies considered more than one exposure.…”

“…The studies on school reopening generally reported on single countries (Germany (n=2)(22, 28), USA (n=1)(25), Switzerland (n=1)(43), Belgium (n=1)(27), Israel (n=1)(45), Italy (n=1)(23)), but one reported discrete estimates for three countries (Denamrk, Germany and Norway)(44), two pooled data from multiple countries globally(16, 35), and one pooled data from multiple European countries(24). Of the three school holiday studies, one reported on Germany(41), one pooled data from 24 countries globally(16), and one pooled data from multiple European countries(17).…”

“…The studies utilised different analytic approaches: regression models (n=24)(14,17,19– 21,25,26,28,30,31,33,35,36,39–42,44,46,48,49,51–53), Bayesian modelling (n=3)(15,18,47), comparison to a synthetic control group (n=4)(24,34,38,44), machine learning approaches (n=2)(43, 50), time series analysis (n=1)(29), and visual representation of changes in transmission over time compared against the timing of school policy interventions, with or without formal statistical analysis (n=4)(16,22,37,45). We identified three study designs used to estimate the effect of school closures: pooled multiple-area before-after comparisons (n=22)(14,15,18–21,24,26,30,32–36,39,40,42,46–50), within-area before-after comparisons(n=7)(23,29,37,38,43,44,53), and pooled multiple-area comparisons of interventions in place at a fixed time point (n=3)(31,51,52).…”

“…Of the school reopening studies, six reported effects on incidence(16,22,24,28,44,45), two on hospitalisations(25, 44), and four on R(23,27,35,43). Two school holiday studies reported an effect on incidence(16, 41), while the other reported on mortality(17). The assumed lag period from school policy changes to changes in incidence rate varied between seven and 20 days, with longer time periods of 26 to 28 days generally assumed for mortality.…”

“…Of the school reopening studies, four were found to be at moderate risk(24,25,28,35), four at serious risk(23,27,43,44), and three at critical risk of bias(16,22,45). The school holiday studies were found to be at moderate (n=1)(41), serious (n=1)(17), or critical (n=1)(16) risk of bias.…”