To investigate the clinical characteristics of adverse events (AEs) after COVID-19 vaccination in patients in South Korea. 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. 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. 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.

Dong Seok Lee, Kook Lae Lee, Ji Bong Jeong, Sue Shin, Su Hwan Kim, and Ji Won Kim. Gut and Liver 1999;0:. https://doi.org/10.5009/gnl19273

Song YJ, et al. Korean Circ J. 2016 Sep;48:e73. https://doi.org/10.4070/kcj.2017.0395

Dong Seok Lee, Ji Yong Ahn and Gin Hyug Lee. Gut and Liver 1999;0:. https://doi.org/10.5009/gnl18389

Background/Aims: We developed a new endoscopic submucosal dissection (ESD) simulator and evaluated its efficacy and realism for use training endoscopists.Methods: An ESD simulator was constructed using polyvinyl alcohol hydrogel sheets and compared to a previous ESD simulator. Between March 1, 2020, and December 30, 2021, eight expert endoscopists from three different centers analyzed the procedure-related factors of the simulator. Five trainees performed gastric ESD exercises under the guidance of these experts.Results: Although the two ESD simulators provided overall favorable outcomes in terms of ESD-related factors, the new simulator had several benefits, including better marking of the target lesion’s limits (p<0.001) and overall handling (p<0.001). Trainees tested the usefulness of the new ESD simulator. The complete resection rate improved after 3 ESD training sessions (9 procedures), and the perforation rate decreased after 4 sessions (12 procedures).Conclusions: We have developed a new ESD simulator that can help beginners achieve a high level of technical experience before performing real-time ESD procedures in patients.