Yeah, sorry I wasn't clear, I was talking about the covid shots. There are studies suggesting negative efficacy against infection after the initial period°. So while I think for hospitalizations and death there is a stronger argument, for infections it's not terribly clear.

° from chat gpt (with all the standard caveats):

Source: "Vaccine effectiveness against SARS-CoV-2 infection with the Omicron or Delta variants following a two-dose or booster BNT162b2 or mRNA-1273 vaccination series: a Danish cohort study" (Published in The Lancet).

Source: "Efficacy of a Fourth Dose of Covid-19 mRNA Vaccine against Omicron" (Published in NEJM).

Source: UKHSA COVID-19 vaccine surveillance reports.