University of Miami pediatrician Judith Schaechter gives a girl an HPV vaccination in 2011. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

A 13-year-old girl gets an HPV vaccination at the University of Miami in 2011. The vaccine protects against the human papillomavirus, which can cause cervical cancer. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

Vaccines against the HPV virus are already used to prevent cervical and anal cancer. Harry Cabluck/AP hide caption

itoggle caption Harry Cabluck/AP

A 13-year-old girl gets an HPV vaccination from Judith Schaechter, a pediatrician at the University of Miami, in 2011. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

Lauren Fant winces as she receives her third and final shot of HPV vaccine from nurse Stephanie Pearson in Marietta, Ga., in 2007. John Amis/AP hide caption

itoggle caption John Amis/AP

An 18-year-old girl winces as she has her third and final shot of the HPV vaccine. John Amis/AP hide caption

itoggle caption John Amis/AP

Connor Perruccello-McClellan, a senior at Providence Country Day School in Rhode Island, has been vaccinated against HPV, something less than 1 percent of U.S. males can say. Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR

Connor Perruccello-McClellan, a senior at Providence Country Day School in Rhode Island, has been vaccinated against HPV, something less than 1 percent of U.S. males can say. Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR