First some background for 1st time readers. Readers who are regular followers can skip this section and go straight to the Thailand study section.
It has long ago been established that the messenger RNA vaccines cause myocarditis, the controversial question now relates to what the actual rate of myocarditis is. The CDC chart below notes a peak myocarditis rate (all boxes shaded in orange are myocarditis rates that are higher than what is expected in the population) in 16-17 year old boy of 75.9 / million (or 1/13,157 ) after dose 2 of the mrna COVID vaccine.
Unfortunately, because of the heavy reliance in the United States on passive reporting, which entails clinicians/ patients voluntarily reporting myocarditis cases, this number is likely an undercount.