Nationwide estimates of SARS-CoV-2 infection fatality rates and numbers needed to vaccinate for SARS-CoV-2 vaccines in 2024 in Austria

ABSTRACT Background Post-pandemic years are characterized by widespread previous population immunisation against COVID-19. Whether and for whom SARS-CoV-2 vaccinations are still justified is unclear. We use nationwide estimates of IFR and literature derived estimates of vaccine effectiveness (VE) to calculate numbers needed to vaccinate to prevent one COVID-19 death (NNV) and for one life-year saved (LYS) in Austria in 2024. Methods In this retrospective analysis we calculate SARS-CoV-2 IFR during 2024 in Austria according to previously published wastewater-based infection estimates and available mortality data. Using literature derived VE estimates we calculate NNV to prevent one COVID-19 death and for one LYS in strata according to age groups, nursing home residency and vaccination in 2024. We repeat analyses with sensitivity range values of parameters. Results In 2024, total IFR was 0.048%. NNV (LYS) in the age groups 0-19, 20-39, 40-59, 60-74 and 75-84 years were very high: e.g. 5,497,526 (151,570), 2,432,498 (92,614), 415,714 (24,777), 35,925 (3,748), and 4,882 (1,009), respectively, in community dwellers. In the 85+ years age group, IFRs of unvaccinated/vaccinated were 0.91%/0.77% for community dwellers, and 1.22%/1.04% for nursing home residents. The 85+ year age group had NNV estimates of 1,215 and 907 (LYS: 525 and 1,896) in community dweller and nursing home residents, respectively. Sensitivity analyses yielded LYS<1,000 only under some favourable assumptions in the 75-84 and 85+ years old age strata. Conclusions In 2024 SARS-CoV-2 IFR was low and NNV and LYS of COVID-19 vaccinations correspondingly non-favourably high, even for very old individuals.