The durability of corona-viral immunity: a comparative evolutionary study

Had to butcher the title from:

"The durability of immunity against reinfection by SARS-CoV-2: a comparative evolutionary study"

It seemed to me that this was more general than just for SARS-CoV-2 so it seemed reasonable to shorten it to corona-viral generally. The immunity studied is related to re-infection and doesn't appear to indicate severity of expected recurring disease.