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HPV vaccination unlikely to promote risky teen sexual behavior
Girls who received HPV vaccination had higher rates of sexually transmitted infections before and after vaccination compared with their unvaccinated peers, according to study findings in JAMA Internal Medicine, suggesting that vaccination does not promote unsafe sexual activity.
“Although several factors have been proposed to explain why HPV vaccination rates in the United States are so low, few barriers have received as much attention as the concern that vaccination against HPV … could promote unsafe sexual activity among females by lowering perceived risks of acquiring a [sexually transmitted infection (STI)] or implicitly endorsing sexual activity by recognizing the need for HPV vaccination,” study researcher Anupam B. Jena, MD, PhD, of Harvard Medical School, and colleagues wrote.
Anupam B. Jena
To analyze whether HPV vaccination was associated with an increase in STIs among females who were vaccinated vs. those who were not, the researchers utilized nationwide insurance claims data from January 2005 through December 2010 from 41 large employers. The study cohort included 21,610 females who were vaccinated against HPV and 186,501 matched unvaccinated females, aged 12 to 18 years.
Females who later were vaccinated against HPV had a rate of 1.6 STIs per 1,000 population vs. 0.9 STIs per 1,000 population among their unvaccinated peers. By the fourth quarter after vaccination, the rate for STIs increased to 2.4 per 1,000 population among vaccinated females vs. 1.4 per 1,000 among unvaccinated females.
The adjusted OR for STIs in the year before vaccination was 1.37 (95% CI, 1.09-1.71) among vaccinated study participants (4.3 per 1,000) and unvaccinated participants (2.8 per 1,000). Rates for STIs increased during the year after vaccination: 6.8 per 1,000 among vaccinated females and 4.2 per 1,000 among unvaccinated females.
During the year after vaccination, the adjusted overall risk for STIs was 1.5 (95% CI, 1.25-1.79), suggesting a difference-in-difference overall risk of 1.05 (95% CI, 0.8-1.38).
“Our difference-in-difference analysis that compared changes in STI rates over time between vaccinated and nonvaccinated females found no evidence of an association between HPV vaccination and higher STI rates,” according to Jena and colleagues.
“Given low rates of HPV vaccination among adolescent females in the United States, our findings should be reassuring to physicians, parents and policymakers that HPV vaccination is unlikely to promote unsafe sexual activity,” they concluded.
In an accompanying editorial, Robert A. Bednarczyk, PhD, of Emory University, said the study findings should not be surprising to physicians. Rather, they serve as reassurance that HPV vaccination does not lead to risky sexual behavior.
“However, this reassurance leaves us with the question, ‘How can we use these findings to address concerns of anxious parents of adolescents?’ ” Bednarczyk wrote.
He suggested physicians use the following points:
- Younger adolescents, aged 9 to 15 years, have greater antibody responses for all HPV types in the quadrivalent HPV vaccine compared with older adolescents, aged 16 to 26 years; and
- Twenty-seven percent of adolescents are sexually active by ages 15 to 17 years vs. 63% by ages 18 to 19 years, according to data from the 2006 to 2010 National Survey of Family Growth.
Further, the 11- and 12-year old well visit is an optimal opportunity to initiate HPV vaccination, as Tdap and meningococcal conjugate vaccines also are recommended at this time. – by Amanda Oldt
Disclosure: Bednarczyk reports receiving research funding from NIH and honoraria and travel support from the US Embassy University Research Program in Tbilisi, Georgia. The other researchers report no relevant financial disclosures.
