This remains to be seen, and some of the experts guess this isn't a major risk. (Obviously it's possible, but there are scads of other viruses that could mutate until they're deadly in humans, too.)
Right now the vaccines are effective against current mutations but yes! It’s very likely that we’ll see more than one covid vaccine during our lifetimes as it mutates.
@OP [cyptus] this is a good question, there is no need for animal resivoir to establish variants/mutation as this happens concurrent with human infection as well.
@spivak you sound on track, the current thought in the lab is polyvalent vaccine. The problems include mRNA duplex interference, meaning 2 species of mRNA may anneal at complementary regions of the sequence to produce localized folding that derails the translation enzymes of the host.
