This following article(not peer reviewed yet, in pre-print) is a , retrospective study which aimed to establish the the rate of myocarditis in children ages 12-17. This rate was stratified according to age groups (12-15 and 16-17 years of age) and sex. The findings were compared with the 120-day COVID-19 hospitalization risk of children of the same age.
The results show that the rate of myocarditis (after 2 doses of an mRNA vaccine) in males 12-15 years old was 162/million, in males 16-17 years old 94/million, females 12-15 years old was 13/million, and in females 16-17 years old 13.4/million. These numbers were considerably higher that the 120-day COVID-19 hospitalization risk of children of the same age which is 44/million.
We still need to wait for the peer review, however, the current information suggests that adolescent boys may not benefit from 2 doses of the currently formulated mRNA vaccines. Alternatives may be to use smaller doses or only one dose.