is it figured out at all why mRNA vaccines cause myocarditis? Lots of people get mild myocarditis throughout their lives without even knowing they had one (we now that because some of those present years later with cardiomyopathy that is put down to a previous viral infection). While AZ is the Russian vaccines are great, it is expected (theoretically) that they will generate weaker and weaker responses because the body will attack the adenovirus that carries the spike proteins before the body gets to mount any measurable immune response to the spike protein, leaving the mRNA vaccines as much better candidates to be the "booster" vaccines. But if everyone is going to get it yearly, it is important to get figure out why myocarditis happen or we (theoretically) may end up with a good number of patients with bad hearts because of the vaccines.