My wife and I caught dengue in Thailand 3 months ago. She started having rapid hair loss two weeks ago and we jokingly said it was probably dengue (it’s a running gag, since that damn thing hit us with a good dozen different symptoms). Joke’s in us; it’s actually dengue. Apparently it’s common to have it happen 2.5 to 3 months down the line. Anyways, I read on it and it’ll apparently go on for a couple months.
In women who have hair loss following a severe illness, a significant telogen effluvium develops and usually reverses in a year or so. In men, if they have genetic balding, they can kick in the genes and then follow their family pattern that is inherited and it could be that it would not reverse in men unlike women who often do reverse. I would expect similar responses to those people who caught Covid-19 Virus and got very sick but as our office is close, we will not see them for some time.