Myocarditis can be caused by lots of different things like viruses (including the common cold), parasites (more common in South America, less so here), various medicines (like penicillin), consuming alcohol, and many other things. You can learn more about the causes from the Myocarditis Foundation: https://www.myocarditisfoundation.org/research-and-grants/faqs/causes-of-myocarditis/
Further, most cases don’t present any significant symptoms, which is why it’s often missed. The Big 10 started screening for it as part of their athlete health program. In fact, when the Big 10 checked athletes who had recovered from COVID-19, they found myocarditis in 2.3% of them (https://jamanetwork.com/journals/jamacardiology/fullarticle/2780548)
To answer your question, if you have a kid with no clinical presentation of myocarditis before the vaccine, and it suddenly appears after vaccination, it’s likely that the vaccine caused that. So far, the evidence seems to be that this happens in about 11 out of 1 million kids. The Big 10 study suggests that 23,000 out of 1 million kids who had COVID-19 have myocarditis.
Big 10 athletes aren’t [i]children[/i], I think a distinction needs to be made here, and this is what the article is referencing.
I’m concerned with the typical “one size fits all” government approach, and no allowances made for age, comorbidities and underlying conditions, and the rest of it, including natural immunity conferred by having acquired Covid 19 and recovered from it.
Also, where are the health “czars” to inform everyone (for example) and explain that metabolic syndrome and/or obesity is the leading indicator on poor outcomes associated with Covid? Nary a peep.