Well, it's pretty easy to know if you are in the 4th category.
Recovered.
Should someone that's been infected and recovered from COVID have to wear a mask?
I would say, until we're fairly confident that having had covid confer permanent immunity, yes, it would be more responsible to wear a mask. Hopefully it does confer permanent immunity, but it would honestly be pretty optimistic to assume that at this point.
Not to mention, nobody around you knows whether or not you're recovered. Wearing a mask is about as close to zero effort as plausible, so wear one anyway out of consideration for others.
