We're talking about ~1:10000 odds for one specific vaccine when vaccinating young males, which is why many countries are no longer using that vaccine for this demographic. Other vaccines are closer to 1:100000, which isn't far from the myocarditis risk of an infection with COVID-19.

The study also shows that there was practically no increase in risk for the third shot (though with a fairly wide CI), so it's possible the risk may just depend on whether someone is immunonaive or not.

> Other vaccines are closer to 1:100000, which isn't far from the myocarditis risk of an infection with COVID-19

The risk is given by the FDA as up to 1:14285 (males aged 12-17) for the second dose:

https://www.fda.gov/media/154869/download

However, a study from Hong Kong found an incidence of up to 1:2700 in the second dose (males aged 12-17):

https://pubmed.ncbi.nlm.nih.gov/34849657/

What we don't know is whether a vaccination would actually prevent Myocarditis in a breakthrough infection. These risks may well not be mutually exclusive. In any case, the risks are not directly comparable unless you assume 100% PCR-confirmed infection risk over six months, which is of course unrealistic.

1:100000 was in reference to the "males < 40" age bucket in the UK study linked by OP. The myocarditis risk from infection for the 12-17 age group appears to be significantly higher according to this study[1] (1:1141), which gets us quite close to the Hong Kong study incidence if we assume two shots after the first dose.

> In any case, the risks are not directly comparable unless you assume 100% PCR-confirmed infection risk over six months, which is of course unrealistic.

I do wonder how unrealistic it is with Omicron, but maybe we'll get lucky and Omicron's less likely to cause myocarditis.

[1]: https://www.medrxiv.org/content/10.1101/2021.07.23.21260998v...