Baka naman hindi. I'm just speculating, but I believe some immunity to the wild strain still confers some protection.
For example , adults get 1 flu shot, but immunologically naive, very young children get 2 flu shots.
The spike proteins on the mutated variants may not latch effectively siguro to antibodies specific to the wild strain (parang tire wrench socket na ibang size won't get the lug nuts off) but in a pinch, a pair of pliers may work. Hindi nga lang the best tool to the job.
Hindi lang naman antibodies ang panlaban ng katawan. Major players also are T & B cells. I have no idea how fast they can
adapt din,
but who knows, baka they can tweak the (new generation of) antibodies to be produced na Omicron or whatever specific variant relatively quickly din, compared to a virus family that your body has never seen before.
In that sense, however much maligned, perhaps we have to give due credit din to the whole inactivated virus vaccine platforms because not spike protein specific orientation nila. Yun nga lang, mahina ang immune response talaga sa inactivated vaccines (not just the COVID ones) because it doesn't challenge the immune system that much:
Antigen presenting cell detects inactivated virus:
"What's that? Raise the Alarm!!!"
Immune system "Central HQ":
"Relax, its just corpses of some unknown alien antigen"
"White blood cells, clean up that mess!"
"B cells, for recording and filing!"