Zombies vs. Vampires
Why aren't vampires the same level of threat as zombies? This is an interesting question because the differences are discussed rather early on in The Undead and Philosophy. Forget for a moment that I think believe vampires are a fictional entity. The book correctly asserts that tradition and folklore indicate that vampires are sentient beings. In contrast, zombies are mindless hosts for a virus that is not sentient and only serves to spread. This means that zombies are part of a mass that has the potential to dominate the planet. Vampires, perhaps due to their increased physical and mental prowess, and of course, immortality, combined with consciousness, would be very selective about whom they admit into their ranks. This is the flaw in the Cornell study's argument. Of course, vampires would be a burden on society, since they are esstentially murders, but their deathly population wouldn't explode expontentially, like zombies' would if left unchecked.
There is also the matter of individuality, which makes becoming a vampire seem so much less terrifiying. A vampire, because (again as folklore declares) they are a fusion of human and demon, still maintains the personality of the human it previously was. In essence, you are still you, though a much more evil, blood-drinking, super-powered you. As a zombie, your body is present, but your individuality is not. Your body becomes an animated shell. And as we all know, being zombie hunters, you should not hesitate to kill the monster no matter who it looks like, because it is no longer that person.
I guess I shouldn't wholeheartedly discount the possibility of vampires; it could be my downfall. However, I like to think that my zombie hunting skills might serve in other instances. Regadless, because of their individuated sense of purpose and selective "breeding", vampires do not pose the threat that global outbreak of the zombie virus does.