HPV vaccination not associated with increase in sexual activity-related outcomes amongst 11 and 12 year-old females

Image: PD/NIH

Key findings:

1. Human papillomavirus (HPV) vaccination in adolescent girls (aged 11 to 12) was not associated with any significant increase in studied sexual activity-related outcomes.

Primer: In 2006, all U.S. girls aged 11 to 12 were recommended to receive the HPV vaccine, with administration acceptable from age 9 to 26. This recommendation, according to the Advisory Committee on Immunization Practices, was suggested to reduce the risk of HPV infection. Among others, early onset of sexual activity and multiple sexual partners are risk factors for HPV infection, which can predispose to cervical cancer.

Media reports have since centered on the idea that the vaccination may lead to increased sexual activity. It is, however, currently unknown whether there is a correlation between HPV vaccination and sexual activity-related outcomes, such as pregnancy and sexually transmitted infections. Although there have been studies attempting to answer this question, major limitations include significant reporter bias and cross-sectional studies involving girls of older ages.

Background reading:

1. Liddon NC, Leichliter JS, Markowitz LE. Human papillomavirus vaccine and sexual behavior among adolescent and young women. Am J Prev Med 2012;42(1):44–52.
2. Forster AS, Marlow LA, Stephenson J, et al. Human papillomavirus vaccination and sexual behaviour: Cross-sectional and longitudinal surveys conducted in England. Vaccine 2012;30(33):4939–4944.

This [retrospective cohort] study: Longitudinal electronic data for 1,398 girls, aged 11 to 12, were analyzed from a managed care organization in Atlanta, Georgia. Of these girls, 493 were vaccine-exposed, and 905 were not vaccine-exposed. The girls had the opportunity to receive the vaccine from July 2006 to December 2007 and follow-up for outcomes were assessed until December 2010. The sexual activity outcomes – based off the International Classification of Diseases – were as follows: 1) pregnancy, 2) sexually transmitted infection testing or diagnosis, and 3) contraceptive counselling. The risk of outcomes for the vaccine-exposed girls were not significantly elevated compared to the non-vaccine-exposed girls (incidence rate ratio = 1.29; 95% CI = 0.92 to 1.80). The incidence rates for Chlamydia infection and pregnancy diagnoses were also not statistically significant (0.06 and 0.07 per 100 person-years, respectively).

In sum: This study is the first to evaluate the sexual activity-related outcomes of adolescent girls recommended to receive HPV vaccination at age 11 to 12. The results agree with numerous previous surveys reporting that most girls did not plan to modify their sexual behaviors despite HPV vaccination. Main limitations of this study include its retrospective nature (the girls may have received vaccines or healthcare counselling outside of the organisation), and that generalizations may not be applicable outside of the study’s age range of 11 to 12.

Indeed, it is important to design public health interventions targeted to reduce the risk of a particular population – in this case, reducing the risk of HPV infection in adolescent girls. It is equally important, however, to know whether the intervention has social and behavioral implications for that population. Although much media and public concern have extensively suggested that vaccination could increase promiscuity among adolescents, this study provides evidence against this notion.

Click to read in Pediatrics

Written by [GL] and [AC]

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