"That is right," Harman says. "Like a good parasite, they tried to escape notice, and apart from a few localised outbreaks that have passed into folklore, it had worked for them -- and for us as well. If we learned anything from those outbreaks, it was that most human casualties were caused by humans when witch-hunt dynamics got out of control. We don't want that again with a population of nearly seven billion humans, and a few hundred vampires."