Exactly this. I'm curious how much we're seeing effects that are present but just haven't been measured previously, because of the size of the newly-vaccinated

Exactly this. I'm curious how much we're seeing effects that are present but just haven't been measured previously, because of the size of the newly-vaccinated population. The second dose is obviously very stressful on the body - people are often down for a couple days dealing with the reaction - so it seems unsurprising that there's /some/ kind of measurable secondary effect. Stress is known to correlate with heart attack.