[alien_]

This should be relatively easy to verify, we have millions of people who have been infected early last year so we can see how many of them got reinfected recently with one of the more recent strains.

If the immune response of the virus is close enough to what a vaccine gives and the mutation rate remains relatively constant, the number of reinfections would probably be a good indication of how much would we need subsequent shots, at least for a yearly renewal cycle.

I wonder, are there any such studies?