Vampires are usually part of the living dead, which means…they’re dead. They’re immune to things like disease or harsh climate, unless these things come from a supernatural source, or rules which bind them. (the sun, for one)
Bu really, you can make wtv rules you want…but in order for it to remain a vampire, some things must be respected. To me, undeath is one. I’m picky with vampires though, and only really like the classical Dracula types.