The problem is that the vaccine is only effective against particular strains of HPV. There's an issue of what economists call “moral hazard” here: if the vaccine leads to increased unprotected sex it may create more new cases than it prevents.

Still, I agree with your reasoning generally.

BTW, I think that worries about teenage sex are misplaced. Our societal problem is not that there's too much teen sex (there's always been a lot) but that there's not enough teen marriage (there used to be a lot more).

I kind of doubt that a vaccine would lead to much of an increase in unprotected sex. There's *tons* of it going on now, and any little thing that can help prevent the spread of HPV is a good thing, in my opinion.

I say this as someone who has a friend whose POS boyfriend brought this nasty bug home to her, and who will now likely never have children because of the effects. She is also at increased risk of cancer.

As far she knew she was in a monogamous relationship, at least until she was diagnosed. Perhaps she was too trusting, but I suspect this same thing happens in married couples as well.