J Korean Med Sci. 2024 Sep 30;39(37):e258. doi: 10.3346/jkms.2024.39.e258.
ABSTRACT
BACKGROUND: This retrospective observational matched cohort study assessed the differences in critical infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the omicron-predominant period of the coronavirus disease 2019 (COVID-19) pandemic. We evaluated the vaccine effectiveness of bivalent mRNA vaccine compared to unvaccinated individuals.
METHODS: We collected COVID-19 case data from the Korean COVID-19 vaccine effectiveness cohort. We calculated the probability of critical COVID-19 cases by comparing the vaccinated and unvaccinated groups.
RESULTS: The risk of being critically infected due to SAR-CoV-2 infection was 5.96 times higher (95% confidence interval, 5.63-6.38) among older individuals who were unvaccinated compared to those who received the bivalent COVID-19 vaccine.
CONCLUSION: Our findings indicate that the bivalent vaccine reduces the disease burden of the SARS-CoV-2 omicron variant, particularly among the older population. Further studies are warranted to determine the effectiveness of booster doses of vaccines for SARS-CoV-2 infection.
PMID:39355951 | DOI:10.3346/jkms.2024.39.e258
