Quick and early success with vaccination

Sexually transmitted HPV declines in US teens

Since a vaccine against HPV was introduced in 2006, 56 percent fewer girls age 14-19 have become infected, said the research announced by the US Centers for Disease Control and published in The Journal of Infectious Diseases.

CDC Director Tom Frieden described the findings as a "wake-up call" that the vaccine works and should be more widely used. Currently, about one-third of girls age 13-17 are fully vaccinated.

 I wonder what percentage of 14 to 19 year old girls were formerly infected, though.  Certainly, go a bit older and the figures are big:

The CDC says about 79 million Americans, most in their late teens and early 20s, are infected with HPV, and every year some 14 million people become newly infected.