Anecdotally, from a HCP: What I have personally seen is that many triple-vaxed young adults have gotten the virus as many as three times in six months. It was clear to me that neither previous infection with Omicron (rev. 1, at least) nor vaccination provided much protection against BA1, BA3, etc. And yeah, that absolutely got my attention. It's not weird to be suspicious about that.
At the same time, I'm following these folks personally very closely-- some of them REALLY closely. I see them more often, and for longer sometimes, than their GPs, who rotate through Student Health or HMOs. None of them are 'dropping like flies.' Some 3x or 4x vaxed older friends who had breakthroughs have longer recoveries than others-- one friend of mine in his late 50s is only hiking 70% as far as he did 5 years ago on the same trail, but it's only been a couple of months, and he keeps seeing steady improvement. But the young people are doing pretty well. I've only heard of one triple-vaxed young athlete who wasn't able to return to competition last semester after infection.
At the same time, I want to know more about the unvaccinated people who are supposedly not getting infected. Are they testing as frequently as the vaccinated cohort? Because here's the other confounding factor: You often have to test three, four, five times to test positive for Omicron. It would make sense to me that unvaccinated folks are more likely to only test when they have to-- say, as part of a study, or for work, or entering the hospital for something else, etc.-- while vaccinated folks are more like to test more frequently. Though I do not know that, it's just an educated guess.
I also feel like we shouldn't ignore the EU's position: They're not so sure about a fourth shot, they wonder about 'tiring out' the immune system. If you're someone like me, with a weird-ass immune system, I'd take that seriously.
I did feel pretty wiped out late this winter and spring, after my third shot, and I had laryngitis for three months! Vaccine reaction? Breakthrough infection? I'll never know. But I've been feeling really strong the last few weeks, and my times are looking real good for my long, steep climbs!
I'd consider a fourth shot, just not anytime soon, and I hope there's a different vaccine available, something more broad spectrum. What seems logical to me: It's probably not a good idea to continue hammering your immune system, either with vaccines or infections, in exactly the same place. Don't let yourself get worn down into a weakened state-- and I think that also means avoiding heavy exercise if you aren't feeling well, either from vax side effects or the infection. (I did hear one news spot that said you SHOULD exercise right after getting vaccinated, which seemed really weird to me -- wish I had better intel on that!) But the cases I see that relapse are generally athletes who went right back out on the field or partiers who returned to near-blackout drinking immediately.
Most people I know are completely healthy after four shots. No one besides me, that I know, felt weaker after the third. I also don't know of a single serious case in anyone who had four shots. Maybe it's happening somewhere, but I've never seen or heard of it. That still doesn't mean that we should all get four shots no matter what. One-size-fits-all medicine has almost killed me on several occasions.