COVID-19 caused second-largest infection mortality disaster in Switzerland, Sweden, and Spain since 1918

A study of continuous monthly mortality data for more than 100 years in Switzerland, Sweden, and Spain found that excess deaths associated with the COVID-19 pandemic reached greater peaks than most other periods of excess deaths since 1918. The findings are published in Annals of Internal Medicine.

Switzerland, Sweden, and Spain are particularly suitable for an over-time perspective of excess mortality because they have reliable continuous data on death counts and were militarily neutral during both world wars. Historical data may help to support planning and preparing for current and future pandemics.

In collaboration with the Swiss Federal Statistical Office, researchers from the Universities of Zurich, Bern and Oslo estimated age-specific, monthly excess deaths from all causes for Switzerland, Sweden, and Spain for 2020 to 2021 and other pandemic periods since the end of the 19th century in chronological order. The authors collected data for monthly all-cause deaths from each country's statistical office and used yearly data on population size and age structure to account for demographic shifts over time. After conducting statistical analysis, the authors found that for all three countries 2020 marked the highest number of excess deaths since 1918. However, excess deaths in 1918 were still estimated to be six to seven times higher than 2020. The relative excess of deaths in 2020 was 12.5 percent in Switzerland, 8.5 percent in Sweden, and 17.3 percent in Spain.

According to the authors, excess mortality in 2020 might have been even higher if not for strong public health interventions worldwide.