Vaccines don’t do much good against rapidly mutating viruses. From el gato malo at boriquagato.substack.com:

vaccines are not magic.
they do not kill or stop or even affect viruses.
all vaccines do is train your immune system to recognize a pathogen and learn a response to prevent it from infecting you.
you store the information on how to make antibodies and how to trigger T-cells etc.
but ALL the vaccines that really do stop you from contracting and spreading diseases have one thing in common:
they work on a “one and done” virus that does not mutate.
measles, smallpox, chicken pox, mumps, rubella, these are all diseases where you get them once and (barring extreme immune suppression or rare malfunction) you never get them again.
this is the realm of plausible vaccine candidates.
a vaccine cannot teach you to do something that you could not otherwise do. it’s just intended to be a safer way to do this that can teach you to resist infection without running the risk of getting infected. we can argue about how good at this which ones are, but it does not change a bigger point:
if your body could not, all by itself, get a disease, recover from it, then never get it again due to acquired immunity, the idea that a vaccine using any currently known modality can allow you to do so is deeply implausible, probably impossible.