well i could make the virus be dormant or something but "luck" or just randomly being immune is not just boring and unlikely, but also it would be a pretty bad virus to kill 98% of the superheroes and just make all the rest get sick, but fight it off some how through...a strong immune system? EDITION: Not only did i add a negative to his power, i also gave him an addition negative for the virus. basically every once in a while, it will return, like it was in remission but never left completely. His sister's still dead as shit though.