First a couple more answers are needed. One - they are reporting effectiveness against hospitalization. Two - they are comparing effectiveness to the unvaccinated. Most of the unvaccinated have some protection due to prior infection(s) at this time. That means today's VE is measuring something different than the original EUA studies reporting VE in the 90s.
From the CDC link: "Further, infections with earlier Omicron lineages, including BA.1 and BA.2, reduce vaccine effectiveness (VE) estimates because certain persons in the referent unvaccinated group have protection from infection-induced immunity."
IIRC, the booster came out during the delta surge, so some of the apparent loss in VE is due to the unvaccinated gaining immunity via sickness. You got boosted, they got sick. Both gained roughly equivalent immunity.
I suggest that the vaccine performs well. Probably a more interesting question is how three dose performed vs a 2 dose population. Or 4 dose vs 3. Or 5 vs 4. Since the readers of this thread are presumably considering whether to get another shot. (Or laughing at all us fools volunteering for the 5G government mind-control chip). The third dose is supposedly important in developing the longterm immunity. It's less clear to me that further boosters provide as much benefit (though this could be due to me not reading enough Covid studies - I decided the national health agencies are doing their job, and I generally follow their advice)
My take on getting a booster is it ought to cause both a temporary effect via increased antibody protection, and a longer lasting incremental effect due to further development of t and B cells. Several of the experts I follow have decided not to get 2nd or 3rd booster as they feel the evidence isn't strong enough. I think they're being pedantic but that's my opinion.
I'm not one of the real experts, though read a lot and try to synthesize and report accurately
