Longitudinal Incidence Study of Clinically-Relevant HPV and Vaccine-Type HPV in Young Online Female Daters

Thesis (Master's)--University of Washington, 2016-08

The sexually transmitted human papillomavirus (HPV) causes cervical cancer, the fourth most common cancer in women world-wide; young women (typically 18- to 24-year-old) have highest levels of infections. Online dating is becoming increasingly prevalent, especially among young women. Better understanding of HPV infection risk in young female online daters is needed to inform public health initiatives and future research efforts. We performed a year-long longitudinal study (2010-2012) of a cohort of 18- to 24-year-old female online daters in the United States, examining their HPV incidence, HPV vaccination history, and sexual behaviors, using self-collected vaginal samples for HPV genotyping and behavioral questionnaires. Kaplan-Meier methods were used to estimate incidence of HPV infection and generalized estimating equations logistic regression was used to identify risk factors for incident infections. The 164 young women that we studied reported a median lifetime number of 6 male sex partners (inter-quartile range: 3-12), with 58.4% having had at least one new male sex partner or multiple male sex partners in the past 6 months. The incidence rate of clinically-relevant HPV infection (high-risk types plus HPV-6 and HPV-11) was 36.9 (95% Confidence Interval (CI): 28.0-48.5) per 100 women-years. Our analysis did not find meeting sex partners online to be a significant factor in incidence of clinically-relevant HPV infections (odds ratio (OR) 0.91, 95% CI: 0.53-1.55, relative to those with at least one male sex partner, but none met online); however, other recent risky sexual behaviors—multiple sex partners, new sex partners, and/or casual sex partners in the prior 6 months (adjusted OR 5.77, 95% CI: 1.42-23.51, for those with all three risk factors versus not sexually active in the prior 6 months)—as well as higher number of total lifetime sex partners (adjusted OR 6.37, 95% CI:1.56-26.05, for those with ≥ 6 relative to 1-2 lifetime sex partners) were significant factors. Nonetheless, in this high-risk cohort we found self-reported history of HPV vaccination to be protective against acquiring vaccine-type HPV (6/11/16/18) (OR 0.27, 95% CI: 0.07-1.03, adjusted for recent sexual behavior and lifetime number of sex partners). Consequently, despite HPV infection being common in young female online daters, vaccination appears protective against vaccine-types, which suggests that public health agencies should continue proactive actions to increasing vaccination uptake and education in order to limit the spread of HPV infection.