I'm equally sure their souls have passed on. Terry leaned back in her chair. So, this virus kills the body and animates it. The heart stops beating, and the red blood cells form loose bonds with each other. The circulatory system becomes a secondary nervous system, and the energy that was once circulated around the body by the movement of blood is instead conducted as chemo-electrical pulses, as in the nervous system.
Vampires have an incredible healing ability.
Given time, a vampire can even regrow a lost limb. But the new muscular-skeletal system needs instructions to do that. The blueprints to your entire body live in every single one of your cells, but by now the virus has already changed those blueprints thoughout the entire body. That is, except for one organ. It doesn't have the same function as when the organism was alive, but it is equally important.