In some house internal estimates, I have been treating "recovered from untested COVID" as something like a 80% risk reduction (because I don't trust people that much to self-diagnose with COVID, though the evidence in that case was quite substantial that it was actually COVID). I would treat "recovered from COVID with confirmed positive and negative test" as something like a 95% risk reduction. I don't currently believe there is much of a risk of being an asymptomatic carrier after more than two weeks having passed of you being tested as recovered.
I'm trying to evaluate the risks associated with spending time with someone who stopped showing symptoms over a month ago.
Most of what I can find is Very Serious Experts saying "No one knows for sure how long immunity lasts. You have to keep wearing masks, even if you've already recovered." The first claim seems misleading (there are only a handful of reinfections in the whole world), but what about the second claim? Could a recovered individual who previously tested negative be asymptomatic and still spread the virus?