Was it harder to study immunity from prior infection than it was to study vaccine effectiveness? I have never participated in a medical study or obviously run one, so honestly have no idea. For a layman it seems like those studies would've been able to be done at numerous stages of the pandemic, all sooner than any vaccine studies. Pretty early on, we adopted the 90 day rule for immunity from prior infection and just said beyond that we don't know and never reported anything different until recently.
But we knew almost right away that Moderna/Pfizer worked well for about 6 months, we knew exactly how effective they were vs. infection, hospitalization and death. We knew %'s on when they started to wane and by how much per month. Then we had similar data vs. delta. Then we had similar data on boosters. Could similar studies not have been done on prior infection, but starting months prior?
In a pandemic, it seems like immunity from prior infection would be the very first thing we would want to know and that studying it wouldn't take anything from the focus on vaccinations. But there's an ocean of things I don't know and maybe this wasn't possible for some reason.
I've always wondered why we've never seen data on second infections, the likelihood and the severity.