Comparing the Effectiveness of Bivalent and Monovalent COVID-19 Vaccines against COVID-19 Infection during the Winter Season of 2022-2023: A Real-World Retrospective Observational Matched Cohort Study in the Republic of Korea

CONCLUSION: Bivalent COVID-19 vaccines showed significantly better protection against infection than monovalent vaccines among adults during the 2022‒2023 winter season. Our results highlight that immunization programs with bivalent vaccines comprising recent variants can be an effective measure to prepare for seasonal COVID-19 …