biostudies-literatureUnknown118Lee DS<h4>Objectives</h4>To investigate the clinical characteristics of adverse events (AEs) after COVID-19 vaccination in patients in South Korea.<h4>Design</h4>Data from the Korean Disease Control and Prevention Agency on AEs from 4 COVID-19 vaccines, including AZD1222, BNT162b2, JNJ-78436735, and mRNA-1273, from February 26, 2021, to August 21, 2021, were assessed. The epidemiological characteristics, clinical symptoms, severity, complications, and mortality were descriptively analyzed.<h4>Results</h4>Overall, 36.3 million individuals who completed the COVID-19 vaccination doses during the study period were included, and 153,183 AEs were reported. Most AEs occurred after the first dose (80.6%) and within a day (63.2%) after vaccination. Of the AEs, 95.5% were nonsevere cases; however, 4.5% were severe. Most mild AEs showed a similar frequency across all age groups, but major severe AEs and mortality events increased with age.<h4>Conclusions</h4>Although there were differences in the frequency of occurrence, various adverse reactions were confirmed in using all 4 COVID-19 vaccines, even with the BNT162b2 (Pfizer-BioNTech) vaccine. Caution is needed, and further research should be continuously conducted.International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases173-182https://www.ebi.ac.uk/biostudies/studies/S-EPMC8904009biostudies-literatureAdverse events following COVID-19 vaccination in South Korea between February 28 and August 21, 2021: A nationwide observational study.PMC8904009Kang HWKim JWLee KLJung YJLee DSfalseAdverse events following COVID-19 vaccination in South Korea between February 28 and August 21, 2021: A nationwide observational study.<h4>Objectives</h4>To investigate the clinical characteristics of adverse events (AEs) after COVID-19 vaccination in patients in South Korea.<h4>Design</h4>Data from the Korean Disease Control and Prevention Agency on AEs from 4 COVID-19 vaccines, including AZD1222, BNT162b2, JNJ-78436735, and mRNA-1273, from February 26, 2021, to August 21, 2021, were assessed. The epidemiological characteristics, clinical symptoms, severity, complications, and mortality were descriptively analyzed.<h4>Results</h4>Overall, 36.3 million individuals who completed the COVID-19 vaccination doses during the study period were included, and 153,183 AEs were reported. Most AEs occurred after the first dose (80.6%) and within a day (63.2%) after vaccination. Of the AEs, 95.5% were nonsevere cases; however, 4.5% were severe. Most mild AEs showed a similar frequency across all age groups, but major severe AEs and mortality events increased with age.<h4>Conclusions</h4>Although there were differences in the frequency of occurrence, various adverse reactions were confirmed in using all 4 COVID-19 vaccines, even with the BNT162b2 (Pfizer-BioNTech) vaccine. Caution is needed, and further research should be continuously conducted.2022-01-01T00:00:00Z2022 May2025-04-29T10:59:50.664Z2025-04-06T19:49:52.05ZS-EPMC89040093527638110.1016/j.ijid.2022.03.007