A polio vaccine means that I won't get polio. A rubella vaccine means I won't get rubella. A Covid vaccine means that I'm only 10-40% as likely to get Covid. (Chime in with more accurate numbers if you have them.) And it means that I'm less likely to get a severe case.
That's not nothing. It's significant, both to me as an individual, and for society-wide epidemiological reasons. But it's not the same as the other vaccines. "One of these is not like the others."
And, yeah, I might get a one-in-a-million breakthrough case for polio or rubella. One of these things still isn't like the others.
So: The Covid vaccine works, but it doesn't work - not in the same way that other vaccines do. (In the same way, the flu vaccine works, but doesn't work.)