Correlates of HPV vaccination and association with HPV-16 and HPV-18 DNA detection in young women

BACKGROUND

Human Papillomavirus (HPV) infection, primarily with high-risk (HR) types 16 and 18, is responsible for causing 17,600 cancers in women and 9,300 cancers in men in the US each year. However, the availability of the HPV vaccination series has substantially reduced the prevalence of vaccine-type HPV.

METHODS

We employed a cross-sectional study design to assess factors associated with HPV vaccine uptake, the effectiveness of HPV vaccination outside of a vaccine efficacy trial, and patterns of HPV vaccination in 21-29 year old women who were eligible to receive catch-up vaccination. Data came from the HOPE (Home HPV or Pap Exam) study, a randomized controlled trial based at the University of Washington, and included self-reported demographic and HPV vaccination information and researcher-reported typing for 14 high-risk HPV types. We used multivariable logistic regression to obtain crude and adjusted prevalence odds ratios and 95% confidence intervals for our associations of interest.

RESULTS

Of 375 subjects, 228 (60.8%) reported receipt of at least one dose of HPV vaccine at study entry, and 16 subjects (4.3%) were infected with HPV 16 and/or 18. Individuals with higher levels of education were more than four times as likely to be vaccinated than those reporting high school education or less. Among vaccinated study participants, 56.5% received their first dose of the HPV vaccination after age 18 and 68.4% after first vaginal intercourse. Unvaccinated women were somewhat more likely to have detectable HPV 16 and/or 18 (OR=2.05, 95% CI: 0.75 – 5.64). Women aged 19-26 at first HPV vaccination dose were more likely to have HPV types 16 and/or 18 compared to women who were vaccinated earlier (OR=3.2, 95% CI: 0.35 – 29.2). Similarly, women who received their first vaccination dose after first vaginal intercourse were more likely to be HPV infected (OR=1.89, 95% CI: 0.22 – 16.2).

CONCLUSION

Our study suggests that increased education, perhaps through targeted campaigns in less educated populations, may reduce disparities in HPV vaccination uptake and that the HPV vaccine is effective at preventing HR-HPV types 16 and 18 among women from 20 to 29 years old outside of vaccine efficacy trials. Generalizable research on patterns of HPV vaccination and vaccine efficacy among larger sample sizes of women in their twenties is needed.