One thing I've wondered about with issues from vaccine side effects is if they are in any way related to how the body would respond if the actual disease was contracted.
This is not to discount the effects or concerns about it -- just curiosity.
Knowing that this is clearly off topic here, one thing that crossed my mind wrt myocarditis amongst the vaccinated is this: amongst athletes, myocarditis is clearly linked to exercising (or even competing) while dealing with an infection (not limited to Covid19 at all, other than that this one seems to be particularly nasty). The risk of inflammation rises when when athletic stress and infection stress (or immune reaction stress, apparently) coincide. This is common knowledge amongst athletes, most would have taken a break from training even if no doctor ever mentioned it.
But we do seem to see an uptick not only amongst the infected but also amongst the vaccinated (note: I do believe that infection is much worse, but vaccinated to infected are roughly 80:20, so it tends to look kind of even). What if the risk of myocarditis was not so much caused by coincidence of training intensity and immune stress but also by coincidence of immune stress and whatever happens during training recovery (when the body does the actual work of adaption, you don't get better during training, you get better afterwards)? When you tell an athlete that they get their shot on Wednesday and they should better take some rest days afterwards, it's as predictable as Wham in December that they will throw in some serious training load on Tuesday. Chances are they'll train extra hard so that they need those rest days anyways. (for me it was Sunday/Monday)
Now the thing I find particularly interesting about this speculation: if this mechanism was real, myocarditis risk not from high training load coinciding with immune stress but/also from immune stress coinciding with post-load recovery, it would be highly unlikely that we'd know about it. Because with naturally occurring immune stress, we don't ever have a clearly defined point in time when it started, and we certainly wouldn't ever deliberately schedule it so that we could arrange for training load to happen right before.
About 105 vaccine recipients reported at least one AEFI symptoms following COVID-19 vaccination (incidence proportion 6.4%, 95% CI: 5.3%, 7.7%). All AEFI reported were minor which were managed by tablet paracetamol and subsided after 1–2 days. Fever (65, 3.98%) was the most commonly reported AEFI followed by myalgia (54, 3.30%) (Fig. 1). About 48 (2.94%) study participants reported 2 or more AEFI, most common being fever with myalgia (19, 1.16%) and fever with headache (18, 1.10%). No severe or serious AEFI was reported among vaccine recipients.
I think adverse just means "not good" as one could also see neutral or even positive effects; one would say severe or serious (as in the text you quoted) as strength modifiers if applicable, but the word "adverse" shouldn't inherently make something sound strong or ever feel synonymous with "serious".
Yeah, I wish we had some research about this. Somehow everybody on internet believes that covid will be always, literally always worse than vaccine side effects.
It is objectively pretty much always the case, this has been studied to death. /r/covid19 has dozens of studies from all over the world quantifying the risks of heart disease for all vaccines, all age cohorts, and vaccination statuses.
This is not to discount the effects or concerns about it -- just curiosity.