Why it’s important: The shot has now been around for 13 years, but many parents remain leery of what they perceive as a newcomer. “They tell me they don’t want their child to be a guinea pig,” says Dr. Hill. Although the vaccination is recommended for girls and boys ages 11 to 12 (and as young as age 9), only 43 percent of adolescents have been fully vaccinated. This study provides reassuring real-world evidence that it works, says Lewis First, M.D., editor-in-chief of Pediatrics. “Getting your son or daughter vaccinated during early adolescence can greatly reduce the chance of getting certain cancers down the road.” And a separate study showed that vaccinated kids are no more likely to engage in earlier or riskier sexual activity. In other words, teens aren’t viewing the vaccine as the green light to start having sex or to toss the condom box. So go for the vaccine. You’ve got nothing to lose.