Introduction Most countries worldwide have experienced excess mortality that coincides temporally with the COVID-19 mass vaccination campaigns. This has led to speculation on the potential long-term effects of the vaccines on mortality risk. Methods The study was designed as a retrospective cohort study and included all individuals aged ≥18 years living in Norway during 1 January 2021 through 31 December 2023. Individuals were categorised as either unvaccinated (received no doses), partially vaccinated (received one or two doses) or fully vaccinated (received three or more doses) from the date of vaccination and onwards. Age-stratified Poisson models were used to estimate incidence rate ratios (IRRs) of death (all causes) between vaccination groups, adjusting for sex, calendar time, county of residence and risk group status (nursing home resident or pre-existing condition with increased risk of severe COVID-19). Results The study included 4 645 910 individuals (49.8% women) with 132 963 deaths during follow-up. There was a higher proportion of individuals that were part of a risk group among fully vaccinated individuals compared with unvaccinated individuals in all age groups and a lower unadjusted rate of death: 51.5 versus 73.6 per 100 000 person years (py) among individuals aged 18–44 years, 295.1 versus 405.3 per 100 000 py among 45–64 years and 3620.2 versus 4783.8 per 100 000 py among 65 years or older. The adjusted IRR of death for the same age groups was 0.42 (95% CI 0.38 to 0.47), 0.39 (95% CI 0.37 to 0.41) and 0.42 (95% CI 0.41 to 0.43), respectively. The differences in the rate of death between vaccination groups were larger among men and peaked during 2022. Conclusion Vaccinated individuals had a lower all-cause mortality rate than unvaccinated individuals during 2021–2023. This difference was larger among men and most prominent following the removal of COVID-19 control measures in 2022 but persisted throughout the study period.
Dahl et al. (Thu,) studied this question.