Well, Kosher Jewish vampires would have a problem: blood is inherently non-kosher. Animal blood, Human blood, whatever. So the question arises: does a vampire need blood to live (or whatever), or is it just a craving? If blood is needed to, um, exist, would animal blood do? If so, then that would be preferable to human blood. If human blood is needed to exist, a kosher Jewish vampire is really in a bind...