HPV vaccine doesn’t lead to teen sex

Parents worried that vaccinating their adolescent daughters against the human papillomavirus (HPV) might encourage them to engage in risky sexual behavior — or to start having sex in the first place — should rest easy, according to a new study released Monday.

Young girls and women who get the HPV vaccine are not more likely to have unprotected sex after receiving it, according to a study conducted by the Cincinnati Children’s Hospital Medical Center that was published online in the journal Pediatrics.

In addition, those women who had not had sex at the time they were vaccinated were not more likely to start, the study found, a result that backs up previous studies that came to the same conclusion.

“I think this study just provides additional reassurance to the data that we already have that the HPV vaccine doesn’t change sexual behaviors,” said Dr. Jessica Kahn, a professor of pediatrics at the medical center and one of the authors of the study.

For the study, more than 300 young women ages 13 to 21 who received the HPV vaccine were surveyed about their beliefs related to HPV and the vaccine as well as their sexual behavior. Then they were polled about the same issues two and six months later to find out whether they had engaged in more or riskier sexual activity as a result of getting the vaccine.

The researchers found no evidence that the vaccines changed the sexual behavior of women within the next six months.

“These are not surprising findings to us,” Kahn said, “but I still think it’s important to point them out so clinicians have the information they need to counsel patients and families appropriately.”

The only unexpected correlation the researchers found was that the women who incorrectly believed that the HPV vaccine would keep them from getting sexually transmitted infections (STIs) other than HPV were no more likely to have sex within the first six months after the vaccination.

HPV is the most common STI in the United States, and certain strains — there are more than 40 — can cause cervical and other types of cancers, according to the Centers for Disease Control.

More than 40 million Americans have it, including 7.5 million young women ages 14 to 24. But two HPV vaccines, Gardasil and Cervarix, have been shown to prevent the spread of the harmful strains of HPV that lead to cervical cancer, and doctors recommend that 11- and 12-year-old girls get vaccinated.

The HPV vaccination rate among 13-to-17-year-old girls increased to 53.8 percent in 2012, from 48.7 percent in 2010, but doctors say that isn’t fast enough and wonder whether the slow uptake could be a result of parental worries that the vaccine encourages kids to have sex.

Previous studies have implied that most parents don’t worry that vaccinating their daughters against HPV will lead to more promiscuous behavior — for example, a study of the parents of 10-to-15-year-olds found that just 24 percent of parents who didn’t support vaccination said it would encourage their kids to have sex earlier, compared with only 9 percent of parents who supported vaccination.