"There was a nasty bug that decimated the hemophiliac population in France back in about 2037," the doc explains, her voice taking on a dry, lecturing tone. "A virus with a long latency period—decades, in some cases. You couldn’t catch it from someone infected, not normally. You could suck face with them, jam with them, share eating utensils, whatever. But if you get a blood transfusion from them, bingo, you’ve got the bug." She pauses. "Okay, that’s still contagious, strictly speaking, because you can catch it from someone who’s got it, even though only through special circumstances."