Quote from Cameron in Alone Time
Gloria: It's a bad time, Cam. Turns out, it wasn't the allergies. I feel terrible. You shouldn't be close to me. I don't want to get you sick.
Cameron: Oh, gosh. No danger of that. I have the immune system of a horse. When I was a kid, I needed a transfusion, and there was a mix-up with the vials. I've contacted Marvel Comics repeatedly, but they don't seem interested.