This isn't WD related, but there was this Free Comic Book Day comic that I picked up titled "Last Blood"...
It was about zombies taking over the planet and the remaining living people where being protected by vampires! They're logic was that if the zombie killed all the people the vampires would die too (the people donated blood to keep the vamps alive)! Anyways, as the issue went on it was revieled that the zombie that started the whole mess in the first place was actually a blood starved, diseased vampire!
It was a pretty cool concept and I would like to read more...