I do think, they are more common stories now, but do not know if it is due to the vaccine or wider news pickup, as back in the day, it was local newspaper and TV stations, mostly of happenings within the region, sparking outrage against coaches pushing young players beyond their limits.
I do not know the answer. Still players pushed beyond limits? A common inoculation that some people may have so genetic disposition, that reacts adversely? If so, where is the test, to see who might have a genetic defect. I say defect, as the vast majority of the population (myself included) have no such reaction, though in my case, I still (even at my age) push to limits, with no ill effects and a family history of heart disease and hypertension. Whatever the answer, it is clear the possible effect does not affect the vast majority of the population. So, it begs the question, is genetic research being done to identify who might be susceptible? I have no personal doubt, the Covid Vaccines, inoculations or whatever you choose to call them have had benefit for the majority, but is there a minority, predisposed genetically to unintended consequence. If so, who is it? Are there genetic identifiers?