Dynamics of infection, vaccination and excess mortality during the COVID-19 pandemic among older individuals-a nationwide analysis.

The Coronavirus Diseases (COVID-19) pandemic led to excess mortality in many countries, i.e., to more deaths than expected. Older individuals generally had higher absolute risks of excess death. The complex dynamics of infection, vaccination and excess mortality have not yet been captured in one comprehensive model. With nationwide and unselected data from Statistics Netherlands, we analyzed the impact of documented infection and vaccination on excess mortality during 2020 and 2021 in the Dutch population aged over 63 on 1 January 2020 (n = 3,826,770) by incorporating relative survival into a multi-state model considering COVID-19 (re)infection, vaccination and death. Background mortality was based on the observed mortality in 2015-2019 per sex, age and month of the year. All analyses were performed for the total cohort as well as stratified per sex and age category. The absolute excess mortality in 2020-2021 was 0.34% (95% confidence interval 0.32-0.37), comprising 4.41% of the observed mortality. It was higher in men (except in the youngest age group) and older individuals. Excess mortality occurred mostly during the first four weeks after a positive COVID-19 test, but also thereafter. If infection occurred after vaccination, excess mortality was still observed, but considerably less than without prior vaccination. These patterns were observed in all groups. In conclusion, these analyses demonstrate the substantial impact of COVID-19 on excess mortality during and after acute SARS-CoV-2 infection in individuals aged over 63 years. Moreover, the results show a reduction of excess mortality after vaccination for all groups in this cohort.