I'll note that in general, I have seen studies indicating that the risk of both MIS-C (linked in GP) and long-covid[1][2] are decreased when comparing vaccinated/unvaccinated post active infection. I've also seen reports that those unvaccinated who experience long-covid sometimes see reduced / cleared symptoms after subsequent vaccination.[3] We also know that antibody titer levels seem to be correlated with a reduction in infection, which is why when those begin to fall off we see more breakthrough infections. And finally we know that building long term T and B cells tends to see a quicker, more effective immune response, both of which should be created post-vaccination.
Given that, I would speculate that vaccination is likely to reduce overall proliferation of cell infection (including directly infecting cardiac tissue via the ACE2 receptors) via having more free-floating antibodies in your system, and is likely to reduce the overall immune-mediated inflammatory response to the virus as it can respond more quickly before the virus has had a chance to proliferate as much. Both of these (reduced inflammation, reduced cell infection) should reduce the risk of myocarditis as a result of infection. And I would speculate that that tracks with other observed reduction of symptoms of infection (MIS-C, long-covid).
Again, speculation on my part; I would definitely want to see studies to confirm or refute that.
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[1]: https://www.thelancet.com/journals/laninf/article/PIIS1473-3...
[2]: https://www.medrxiv.org/content/10.1101/2022.01.05.22268800v...
However, _in my opinion_ with how infectious omicron is, it is likely inevitable that everyone will eventually be exposed. The literature (linked in my GP) currently seems to indicate that vaccines have a lower risk of myocarditis than an active SARS-CoV-2 infection. Most literature that I've seen (so far) indicates that occurrences of post-vaccination myocarditis tends to be rare, and not life-threatening, and the patients tend to recover quickly.[1]
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[1]: https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.0...
https://vinayprasadmdmph.substack.com/p/uk-now-reports-myoca...
based on this Nature paper
https://www.nature.com/articles/s41591-021-01630-0.pdf
"Yes, sorry to break it to you, vaccines can have risks of myocarditis EXCEEDING risks of myocarditis from infection. Pls stop saying otherwise."
However, for 16-40, Patone, et al[1] estimates that myocarditis incidence is around 2/mil for AstraZeneca, 1/mil for Pfizer per does, and 6/mil for Moderna first dose, 10/mil for the second, compared to 40/mil for an active infection.
Singer, el al[2] (pre-print) states that males < 20 are roughly 6x less likely to develop myocarditis from vaccination compared to an infection.
The AMA[3] also has some info on both myocarditis and MIS-C. 95% of those who developed MIS-C were unvaccinated, and up to 40% required some sort of respiratory or cardiovascular life support (compare to 0% of those vaccinated). Also states ages 12-15 appear less likely to develop myocarditis than the 16 - ~40 range.
Everything I've read so far is that myocarditis from vaccination usually resolves fairly quickly.
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[1]: https://www.nature.com/articles/s41591-021-01630-0.pdf
[2]: https://www.medrxiv.org/content/10.1101/2021.07.23.21260998v...
[3]: https://www.ama-assn.org/delivering-care/population-care/unv...