Is it possibly an unaccounted for side effect of the vaccine?
"Healthy boys may be more likely to be admitted to hospital with a rare side-effect of the Pfizer/BioNTech Covid vaccine that causes inflammation of the heart than with Covid itself, US researchers claim."
https://www.theguardian.com/world/2021/sep/10/boys-more-at-r...
https://www.acc.org/latest-in-cardiology/articles/2021/09/28...
Note while no deaths were found in the studies, the fact that these small studies are finding inflammation common suggests the effect is much larger than the (very unusual) cases being intensively surveilled in the case of inoculation. (I.e. you find what you're looking for...)