Re: Vaccine for 31 year old
The age limit is set to provide maximum benefit to the most appropriate candidates, and to give a limit to insurance providers.
That does NOT mean that a woman with no HPV would not benefit from the vaccine. It just means that your insurance is not likely to cover it, but you can still probably get it from your doctor.
Basically, they don't want to give it to a woman over that age because the odds of her not having already been exposed are pretty slim.
But since you say you're a virgin you could still be completely hpv-free and a perfect candidate for the vaccine. Ask your doctor.