Impact of COVID-19 vaccination on mortality from competing causes: A nationwide Czech study, 2022

Abstract Background COVID-19 vaccination significantly reduced virus-related mortality. Various studies show varying mortality from other causes in vaccinated versus unvaccinated populations, without clear evidence of a direct vaccine effect. Similar patterns have emerged in other vaccination programs, suggesting differences in health status, risk behaviour, or prevention strategies. This research aims to evaluate mortality differences between ever- and never-vaccinated populations for specific causes of death, providing indirect insights into underlying factors. Methods The research uses data from the National Information System of Infectious Diseases, tracking 7,496,182 adults (18+ at least once vaccinated or tested) during 2022. Cox models evaluated mortality risk by vaccination status, age group, and previous registered COVID-19 infections (separately for males and females). Hazard Ratios (HR) were calculated for COVID-19 mortality and five competing causes of death: circulatory diseases, malignant neoplasms, infectious diseases, external causes, and all other causes. Results COVID-19 mortality was 18.9 times higher in unvaccinated men and 19.2 times higher in unvaccinated women (p < .0001), confirming vaccination's strong direct protective effect. Ever-vaccinated individuals had a lower risk of death from non-COVID causes (HR from 0.57 for infections to 0.85 for external causes in males; and from 0.53 for infections to 0.86 for external causes for females). This confirms a substantial direct effect of vaccination against COVID-19 and a weaker indirect (selection or behavioural) effect on other causes. Conclusions The results are robust thanks to a large, detailed dataset of individual data. Mortality differences suggest that vaccinated and unvaccinated populations differ. However, no significant differences in the health status were proven. Differences in mortality from external causes indicate behavioural or selection factors that drive the inner population variations. Key messages • Mortality for vaccinated and unvaccinated individuals differed for non-COVID-19 causes. • No significant health differences indicated that variations stem from selection effects and risky behaviour.