Genc Bahce, YaseminAcer, OmerOzudogru, Osman2024-12-242024-12-2420230343-86511432-0991https://doi.org/10.1007/s00284-023-03322-zhttps://hdl.handle.net/20.500.12604/5974Older age (>60 years) has been identified as the main risk factor for COVID-19. In this study, we aimed to evaluate the efficacy of Pfizer-BioNTech and CoronaVac vaccines against COVID-19 infection, serious illness, and mortality in the geriatric population. We found that 2 doses of CoronaVac vaccine were ineffective in protecting against COVID-19 infection in people over 65 years of age, while the vaccine efficacy (VE) of the mRNA vaccine against COVID-19 was 80% (95% CI 70-87). The VE of full vaccination with BioNTech was 89% (95% CI 53-97) against hospitalization, 79% (95% CI 0-97) against death, and 79% (95% CI 0-97) against intensive care unit (ICU) admission. However, the VE of full vaccination with CoronaVac was 50% (95% CI 33-63) against hospitalization, 53% (95% CI 26-70) against ICU admission, and 56% (95% CI 30-73) against death. In conclusion, we found that the mRNA vaccine has higher efficacy against severe COVID-19 infection and mortality in the geriatric population than the inactivated vaccine. Booster doses of vaccines should be considered in increasing the effectiveness of inactivated vaccines. Given the potential of SARS-CoV-2 mutations evading vaccination protection and the risk of reduced immunity over time, regular monitoring of vaccine effectiveness in the real world is critical.eninfo:eu-repo/semantics/openAccessArticle806Q3WOS:000984914200001Q32-s2.0-851589395103716045310.1007/s00284-023-03322-z