Patone et al.: "Risk of myocarditis following sequential COVID-19 vaccinations by age & sex"; Myocarditis risk was increased during 1-28 days after a 3rd dose of Pfizer (IRR 2.02, 95% CI 1.40, 2.91)

Associations were strongest in males under 40 years for all vaccine types with an additional 3 (95%CI 1, 5) & 12 (95% CI 1,17) events per million estimated in the 1-28 days following a first dose

"For BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna), the risk of myocarditis after mRNA vaccination was 8 times and 30 times higher than that of the unvaccinated control groups, respectively."

“Associations were strongest in males younger than 40 years for all vaccine types with an additional 3 (95%CI 1, 5) and 12 (95% CI 1,17) events per million estimated in the 1-28 days following a first dose of BNT162b2 and mRNA-1273, respectively; 14 (95%CI 8, 17), 12 (95%CI 1, 7) and 101 (95%CI 95, 104) additional events following a second dose of ChAdOx1, BNT162b2 and mRNA-1273, respectively; and 13 (95%CI 7, 15) additional events following a third dose of BNT162b2, compared with 7 (95%CI 2, 11) additional events following COVID-19 infection.”

SOURCE:

Risk of myocarditis following sequential COVID-19 vaccinations by age and sex