COVID-19 vaccination in the pediatric age and risk for myocarditis

Abstract Background There are some concerns about the cost/benefit ratio of Covid-19 vaccination in children and young adolescents age due to the greater response to immune stimulation. Myocarditis is a feared adverse event (AE). Methods On January 4, 2022 we searched the Pubmed and EMBASE datasets for population studies assessing myocarditis events in pediatric subjects, and US nationwide data about COVID-19 vaccinations and AEs. Results The studies selected (n=10) were highly heterogeneous, and did not include subjects <12 years. The estimated incidence of myocarditis in the US was 2.80 over 100,000 in fully vaccinated individuals (i.e., receiving two doses of mRNA vaccines or received one dose of a single-dose vaccine) aged 6–17 years. No events were reported <5 years (n=9,985). The incidence of myocarditis was 1.05 over 100,000 in those aged 18–64 years, and 2.75 over 1,000,000 ≥65 years. The incidence of fatal or life-threatening myocarditis was 3.78 over 1,000,000 6–17 years, 1.78 over 1,000,000 18–64 years, and 8.54 over 10,000,000 ≥65 years, with the same order of magnitude than the odds of being struck by lightning. The incidence of COVID-19 myocarditis is 1.33 in 1000 <16 years, i.e., 47.5-fold higher than fully vaccinated individuals. Conclusions The reported incidence of myocarditis in subjects aged ≥12 years is slightly higher in males and after the second dose, but extremely low. No case of myocarditis <5 years were reported in the US. In fully vaccinated individuals aged 6–17 years, the estimated incidence of myocarditis was far lower than the risk of COVID-19 myocarditis. Funding Acknowledgement Type of funding sources: None.