It saturates the body to such a degree that the "worst" vaccine in the "worst" age group creates an extra 30 cases of myocarditis per million people?
Edit: 100 per million, thanks for the correction. 0.01% of people.
Edit: 100 per million, thanks for the correction. 0.01% of people.
That's still very safe, but it's good to be accurate.
(I am an under 30yo male who is fully vaccinated, just to be clear)