Nationwide Incidence and Clinical Outcomes of COVID-19 Vaccination-Related Myocarditis in Korea

Aims: A comprehensive nationwide study on the incidence and outcomes of COVID-19 vaccination-related myocarditis (VRM) is in need. Methods and results: Among 44,276,704 individuals with at least one dose of COVID-19 vaccination, the incidence and clinical courses of VRM cases confirmed by the Expert Adjudication Committee of the Korea Disease Control and Prevention Agency were analyzed. COVID-19 VRM was confirmed in 480 cases (1.08 cases per 100,000 persons). VRM incidence was significantly higher in men than in women (1.35 vs. 0.82 per 100,000 persons, P < 0.001) and in mRNA vaccines than in other vaccines (1.46 vs. 0.14 per 100,000 persons, P < 0.001). Incidence was highest in males aged 12–17 years (5.29 per 100,000) and lowest in females ≥70 years (0.16 per 100,000). Severe VRM occurred in 95 cases (19.8% of total VRM; 0.22 per 100,000 vaccinated), including 85 ICU admissions (17.7%), 36 fulminant myocarditis (7.5%), 21 ECMO therapies (4.4%), 21 deaths (4.4%), and 1 heart transplantation (0.2%). Eight of 21 deaths were autopsy-proven sudden cardiac deaths (SCD) attributable to VRM; all were <45 years and had received mRNA vaccines. Conclusion: Although COVID-19 VRM was rare and generally showed favorable clinical courses, severe VRM occurred in 19.8% of VRM cases. SCD should be closely monitored as a potentially fatal complication of COVID-19 vaccination.

Jae Yeong Cho, Kye Hun Kim, Nuri Lee, Soo Hyeon Cho, Seung Yun Kim, Eun Kyoung Kim, Jae-Hyeong Park, Eui-Young Choi, Jin-Oh Choi, Hyukjin Park, Hyung Yoon Kim, Hyun Ju Yoon, Youngkeun Ahn, Myung Ho Jeong, Jeong Gwan Cho, COVID-19 Vaccination Task Force Adverse Event Investigation Team