That last part is complicated because it’s a function of not just the vaccines but also the virus: some mutate more readily than others both by how well they tolerate mutations and how rapidly they spread (more cases = more chances to get the next big mutation). Our influenza vaccines have a similar problem because that’s also a respiratory virus which mutates frequently. Something which only spread by skin contact might, for example, be an easier target simply because it has a much slower spread and thus mutation rate — nobody gets on a bus and licks all of the other passengers!