Despite the recommendations made by national immunization advisory committees around the world, HPV vaccination rates, especially in the United States, remain suboptimal. For example, in the United States in 2015 only 62.8% of 13-17 year old girls and 49.8% of 13-17 year old boys had received at least one dose of the HPV vaccine and the numbers are even lower for series completion (41.9% and 28.1% respectively). When asked about barriers vaccinating their children for HPV, some parents cite concerns about Risk Compensation. That is, they are concerned that vaccinating their children against a sexually transmitted infection (STI) will result in increased risky sexual behaviors. Critics of the vaccine have expressed this concern throughout the world, from the U.S., to Canada, to the United Kingdom. However, our recent systematic review of the literature found no evidence of risky sexual behavior after vaccination 1.There were 20 studies included in the final analysis and both behavioral outcomes (such as number of sexual partners and age at sexual debut) and biological/health outcomes (such as STI diagnoses and pregnancies) were examined.

Behavioral Outcomes
Almost all of the behavioral outcome studies found no association between vaccination status and subsequent sexual activity. In fact, there were some longitudinal studies that found decreased sexual activity after vaccination. Although some cross-sectional studies did find vaccinated participants were more likely to have engaged in sexual intercourse than unvaccinated participants, these studies also noted that many of their participants (between 45% and 62%) were sexually active prior to HPV vaccination. Therefore, these results may be more indicative of a woman engaging in sexual behavior, then seeking out protective measures as opposed to vaccination causing increased sexual behavior. Furthermore, previous studies have shown that providers are more likely to recommend HPV vaccine to patients they believe are sexually active or not in a monogamous relationship.
Other studies examined more specific risky sexual behaviors, finding no association between HPV vaccination and behaviors such as: age at sexual debut, number of sexual partners, and contraception use. In fact, some studies found that vaccinated participants reported less risky sexual behavior as compared to the unvaccinated participants. These results provide compelling evidence that there is no increase in risky sexual behaviors after HPV vaccination.

Biological Outcomes
Several studies have examined biological/health markers of risky sexual behavior, including STI/HIV testing, STI/HIV diagnosis, pregnancies, and abortions. There was no evidence of increased STI/HIV testing or diagnosis in the vaccinated sample. Furthermore, one study found that it participants who did not receive HPV vaccine had higher rates of chlamydia. Two studies examined a composite measure of STIs and pregnancies and neither found any relationship with vaccination status. Other studies found no associations between vaccination and pregnancy or abortion, and one reported that among participants who had a history of abortion, none of them had received HPV vaccine. These biological/health outcome studies lend further support to the findings of the sexual behavior studies that show no association of HPV vaccination with increased risky sexual behavior.

Conclusions
The consistent, replicated findings across the 20 studies examined in our systematic review provide strong evidence refuting the proposed association between HPV vaccination and risky sexual behavior. The 20 studies, which utilizing at least four distinct study designs and included a total of 521,879 participants, found no evidence for increased numbers of sexual partners, younger age of sexual initiation, decreased use of contraception (including both condoms and hormonal contraceptives), increased STI diagnoses, increased pregnancy rates, or increased history of abortion among those vaccinated against HPV. In fact, some studies found that vaccinated women engaged in fewer risky behaviors than unvaccinated women. The findings from our systematic review should alleviate any parental concerns that HPV vaccination will lead to risky sexual behaviors.

References

1. Kasting ML, Shapiro GK, Rosberger Z, Kahn JA, Zimet GD. Tempest in a teapot: A systematic review of HPV vaccination and risk compensation research. Hum Vaccin Immunother. 2016;12(6):1435-50. doi:10.1080/21645515. 2016.114115