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

Abstract

Introduction: 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. Methods: 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. All treatment was discontinued after 2 months. Average NAPSI score on each hand was analysed. Results: 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. Conclusion: Data from the national registry in Singapore indicate an increased incidence of pericarditis and myocarditis in younger men after COVID-19 mRNA vaccination. Keywords: COVID-19 vaccine, myocarditis, pericarditis

Risk of myocarditis and pericarditis in mRNA COVID-19-vaccinated and unvaccinated populations: a systematic review and meta-analysis

“…Second, all myo/pericarditis cases in the six included studies were adjudicated by at least two methods, minimising the risk of misclassification that can arise from relying on diagnosis codes alone. Third, while the rates in our study are similar to those reported in other studies that examined only the incidence rate of myo/pericarditis following mRNA COVID-19 vaccination among the vaccinated individuals,13 81 93–95 we attempted to overcome some of their limitations by also including the rate of myo/pericarditis in the unvaccinated individuals and calculating the overall RR. We also conducted an analysis restricted to shorter risk intervals by including only confirmed cases of myo/pericarditis that were reported within 30 days following vaccination, and excluding the two studies that used historical comparator cohort group; such that we had only concurrent comparators which comprised unvaccinated individuals rather than prepandemic historical records due to concerns about how the COVID-19 pandemic has affected the rate of patients seeking medical care 96.…”