Level 2 (mid-level) evidence

Routine human papillomavirus (HPV) vaccination is recommended for all children 11-12 years old and is approved in adolescents and young adults up to 26 years old for the main purpose of preventing HPV associated cancers, particularly cervical cancer (MMWR Recomm Rep. 2014;63[RR-05]:1; CACancer J Clin. 2007;57[1]:7; Obstet Gynecol. 2014;123[3]:712; Pediatrics. 2012;129[3]:602). Though vaccination rates have been steadily increasing since the quadrivalent HPV vaccine first received FDA approval for girls and women in 2006, missed vaccination opportunities are common. In 2013 vaccine coverage for girls aged 13-17 years was 57.3% for ≥ 1 dose and only 37.6% received all three recommended doses (MMWR Morb Mortal Wkly Rep. 2014;25;63[29]:620). Several barriers to vaccination have been reported (Prev Med. 2014;58:22), but the greatest attention has been paid to the effect of vaccination on adolescent sexuality. Specifically, some people have argued that HPV vaccination will lead to earlier sexual activity and increase risky sexual behaviors (J Health Commun. 2010;15[2]:205; BMC Public Health. 2014;14:700). A recent study compared the incidence of sexually transmitted infections in 21,610 female adolescents aged 12-18 years in the United States receiving at least one dose of the HPV vaccine and 186,501 matched unvaccinated female adolescents using longitudinal insurance data (JAMA. Intern Med. 2015; Feb 9 early online)

Vaccinated and unvaccinated adolescents were matched for age, residence, and health plan, but multiple nonvaccinated controls were allowed for each vaccinated adolescent. Vaccination rates significantly varied by region and the lowest vaccination rates were found in the South. The rates of sexually transmitted infections for the time period including 1 year prior to vaccination and 1 year after vaccination were determined for vaccinated and unvaccinated adolescents. In the year before vaccination, adolescents receiving the HPV vaccine had a significantly higher incidence of any sexually transmitted infection and a higher percentage of oral contraceptive use. To control for these baseline differences, a difference-in-difference analysis was performed comparing the change in the incidence of sexually transmitted infection from 1 year before vaccination to 1 year after vaccination in the vaccinated and unvaccinated groups. The rates of sexually transmitted infections increased in both the vaccinated and unvaccinated populations in the year after vaccination. The difference-in-difference analysis, however, showed no significant difference in sexually transmitted infections comparing vaccinated and unvaccinated adolescents (odds ratio 1.05, 95% CI 0.8-1.38). Similar results were found in subgroup analyses of adolescents aged 12-14 years, adolescents aged 15-18 years, and in adolescents using contraceptive medications. 

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The results of this study suggest that HPV vaccination is not associated with an increase in sexually transmitted infections. Although adolescents receiving the HPV vaccine had a higher rate of sexually transmitted infections, this difference was established before vaccination occurred and was not the result of HPV vaccination. In contrast, this result suggests that adolescents at an increased risk for sexually transmitted infection may be receiving the HPV vaccine at a higher rate, possibly due to a sexually transmitted infection diagnosis. The increased incidence of sexually transmitted infections observed in both groups of adolescents over time highlights the importance of early HPV vaccination before potential HPV exposure.

Alan Ehrlich, MD, is a deputy editor for DynaMed, Ipswich, Mass., and assistant clinical professor in Family Medicine, University of Massachusetts Medical School in Worcester. 

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