The risk of myocarditis after mRNA vaccination was 8 times and 30 times greater than unvaccinated control groups for BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna), respectively.
The largest association for myocarditis following the Moderna jab was 44 times higher risk for persons aged 18 to 24 years.
As for the Pfizer shot, in relation to the same age group, the risk was 13 times higher.
The new study's goal was to provide an assessment of association with vaccines across sex and age groups.
The study analyzed 1,612 cases of myocarditis and 1,613 cases of pericarditis in France from May 12, 2021, to Oct. 31, 2021, involving 32 million people aged 12 to 50 years who received 46 million doses of mRNA vaccines.
It is limited by using solely hospital discharge diagnoses. Therefore, it does not include those who may have died before being hospitalized or those whose symptoms were not severe enough to be hospitalized.
The authors of the study didn't analyze the effect of booster vaccination since it is not yet recommended for young adults in France.
In the United States, however, booster injections are mandated by colleges and universities, employers, and even some state public health departments irrespective of age or prior infection.