> Overall, the relatively higher intra-host diversity among vaccinated individuals and the detection of immune-escape mutations, despite being rare, suggest a potential vaccine-induced immune pressure in vaccinated individuals.
Pretty much everything puts evolutionary pressure on the virus. If the host keels over 1s after infection, that line's going to die out. If the antibodies from vaccination/infection target an invariant portion, the virus might effectively die out (polio, measles, etc). Ideally, between vaccination and infection we've proceeded to an equilibrium - the nasties have been outcompeted or died out and (way) fewer people have been keeling over. If/when Covid truly behaves like the flu it will be another of the coronaviruses causing colds of varying severity.