Regardless, I Am Legend depicts an entirely different scenario from the one I'm referring to. I'm talking about vampires preying on a large group of people, which shifts the morality involved considerably. And even if it is possible to cure them, does that mean you should just let them keep on killing and turning people until the cure is found? That you shouldn't proactively protect your citizens? And what if some of them don't want to be cured, and would rather go on eating the flesh of men for all eternity? Should you just "live and let live"? Of course not.