Pericarditis and myocarditis after COVID-19 mRNA vaccination in a nationwide setting

• Published in: Annals of the Academy of Medicine, Singapore Vol. 51; no. 2; p. 96
• Main Authors: Yap, Jonathan, Tham, Mun Yee, Poh, Jalene, Toh, Dorothy, Chan, Cheng Leng, Lim, Toon Wei, Lim, Shir Lynn, Chia, Yew Woon, Lim, Yean Teng, Choo, Jonathan, Ding, Zee Pin, Foo, Ling Li, Kuo, Simin, Lau, Yee How, Lee, Annie, Yeo, Khung Keong
• Format: Journal Article
• Language: English
• Published: Singapore 20.02.2022
• Subjects: Adolescent; Adult; Child; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 Vaccines - adverse effects; Female; Humans; Male; Middle Aged; mRNA Vaccines; Myocarditis - complications; Myocarditis - etiology; Pericarditis - epidemiology; Pericarditis - etiology; RNA, Messenger; SARS-CoV-2; Vaccination - adverse effects; Vaccines, Synthetic; Young Adult
• ISSN: 0304-4602; 2972-4066; 0304-4602
• DOI: 10.47102/annals-acadmedsg.2021245

Despite reports suggesting an association between COVID-19 mRNA vaccination and pericarditis and myocarditis, detailed nationwide population-based data are sparsely available. We describe the incidence of pericarditis and myocarditis by age categories and sex after COVID-19 mRNA vaccination from a nationwide mass vaccination programme in Singapore. The incidence of adjudicated cases of pericarditis and myocarditis following COVID-19 mRNA vaccination that were reported to the vaccine safety committee between January to July 2021 was compared with the background incidence of myocarditis in Singapore. As of end July 2021, a total of 34 cases were reported (9 pericarditis only, 14 myocarditis only, and 11 concomitant pericarditis and myocarditis) with 7,183,889 doses of COVID-19 mRNA vaccine administered. Of the 9 cases of pericarditis only, all were male except one. The highest incidence of pericarditis was in males aged 12-19 years with an incidence of 1.11 cases per 100,000 doses. Of the 25 cases of myocarditis, 80% (20 cases) were male and the median age was 23 years (range 12-55 years) with 16 cases after the second dose. A higher-than-expected number of cases were seen in males aged 12-19 and 20-29 years, with incidence rates of 3.72 and 0.98 case per 100,000 doses, respectively. Data from the national registry in Singapore indicate an increased incidence of pericarditis and myocarditis in younger men after COVID-19 mRNA vaccination.