The increase in myocarditis from the vaccine is well-documented. (And very small.)
COVID causes myocarditis too (even for young people unlikely to die from COVID itself), at much higher rates. So you only need a 20% chance of contracting COVID for the vaccine to be net positive in the least obviously positive age group.
I am not a physician, but I expect that decades hence we will see the health effects of repeated Covid infections. I'm guessing specifically around cardio health and dementia risk.
COVID causes myocarditis too (even for young people unlikely to die from COVID itself), at much higher rates. So you only need a 20% chance of contracting COVID for the vaccine to be net positive in the least obviously positive age group.