Girls who are vaccinated for human papillomavirus (HPV) are no more likely to engage in sexually risky behaviors than girls who don’t receive the vaccine, says a recent study published in the journal Pediatrics.
While the HPV vaccine protects against cervical cancer, it’s also effective in fighting genital warts caused by the virus. For that reason, the fact that the injection is given to girls aged 11-12 as part of the childhood vaccination schedule made some parents uncomfortable with the fact that adolescents were being targeted for a sexually transmitted disease. Some feared it would even give pre-teens a false sense of security and encourage them to become sexually active.
In order to assess whether HPV vaccination (there are two shots, Gardasil and Cervarix) is associated with changes in sexual behavior, researchers from the Kaiser Permanente Center for Health Research and Emory University followed over 1,000 girls who were members of the Kaiser Permanente health plan in Georgia in 2006 and 2007, during the first 18 months the Gardasil vaccine was available. Among the participants, 493 had received at least one dose of the vaccine, which requires three doses over six months, and the other 905 girls received another adolescent vaccine that was not HPV-related.
The researchers followed the girls for three years and tracked their behaviors associated with sexual activity such as being tested for or diagnosed with a sexually transmitted infection (STI), taking a pregnancy test and receiving counseling on contraceptives. They found no differences between these sexual activity outcomes among girls who were vaccinated and those who were not.
Overall, about 10% of the total participants had one of the sexual activity outcomes and less than 1% were diagnosed with an STI or had a positive pregnancy test. The vaccinated girls did not have a higher rate of counseling, testing or diagnosis. “If HPV vaccination was “a license for sex,” we would have expected to see more adverse outcomes shortly after vaccination, when the girls were more aware of their recent vaccination status,” the authors write.
The data support other recent data addressing the safety of the vaccine; while the shots can cause fainting, they aren’t associated with more serious side effects, according to a study funded by Gardasil’s manufacturer, Merck, and conducted by researchers at a Cal. Kaiser Permanente group.
HPV is the most common sexually transmitted infection, with about 50% of sexually active men and women contracting it at some point during their lives. Early sexual behaviors and multiple sexual partners are risk factors for infection, but other studies have hinted that the vaccine may not encourage sexual activity; in one review of 1,398 girls ages 11 to 12, there was no indication that that girls who received the vaccine planned to engage in more sexual activity. These studies, however, were largely based on self-reported data. The current study is one of the first to evaluate sexual activity after vaccination among this age group based on clinical data.
“This provides a clinical validation of what’s been seen with the prior self-reported surveys, and can hopefully provide some reassurance to physicians and parents that the concern really may be unfounded,” says lead study author Robert Bednarczyk, clinical investigator with Kaiser Permanente’s Center for Health Research Southeast, and epidemiologist with Emory University.. “We hope we can move beyond this concern over increases in sexual activity, and hopefully once all this evidence is out there, we can work to increase HPV vaccine uptake.”
Physicians have recommended vaccines to prevent HPV since 2006, but according to the study authors, by 2010 less than half of eligible girls received a single dose of the HPV vaccine Gardasil. Barriers to getting vaccinated include the shot’s cost (nearly $400 for all three doses) and the need to come in for multiple doses, but concerns over vaccinating young girls against a sexually transmitted disease also kept many parents from having their daughters immunized.
“The extent to which parental concerns about sexual activity dominate is really unclear, but it has come out in some media articles and seems to pop up periodically,” says Bednarczyk. Data from studies like his should help to alleviate concerns about the shot, and hopefully contribute to lowering rates of cervical cancer as well as spread of genital warts.