Abstract
The emergence of the omicron variant and its sub-lineages has necessitated vaccine updates for coronavirus disease 2019. In September 2023, the U.S. Food and Drug Administration approved an updated BNT162b2 vaccine targeting the omicron XBB.1.5 variant, which was initiated in Korea in October 2024. This study demonstrates the adverse events reported through active nationwide surveillance after XBB.1.5 vaccination in Korea. Since October 19, 2023, the Korea Disease Control and Prevention Agency has conducted daily Short Message Service surveys to collect data on health issues, fever, vaccination site reactions, systemic symptoms, impact on daily life, and healthcare visits. Among 20,180 respondents, 27.9% reported health issues. Adverse reactions peaked on day 1 (28.7%), including pain at the vaccination site, muscle pain, fatigue, and fever. These findings elucidate the short-term safety of the XBB.1.5 vaccine and support its co-administration with the influenza vaccine, reducing vaccine hesitancy and achieving herd immunity.