Vaccination of young women decreases human papillomavirus transmission in heterosexual couples: findings from the HITCH cohort study.

Vaccination against human papillomaviruses (HPV) prevents HPV infections and consequently, cervical lesions. However, the effect of vaccination on HPV transmission within couples is unknown.We used data from HITCH, a prospective cohort study of heterosexual couples (women aged 18-24y) in Montreal, 2005-2013. Vaccination history was self-reported. Genital samples were tested for HPV DNA by PCR (Linear Array). Type-specific viral loads were quantified using real-time PCR. Odds and hazard ratios (OR/HR) were estimated using multi-level mixed-effects logistic regression and a parametric model for interval-censored survival-time data, respectively. Differences in viral loads were evaluated using the Friedman's ANOVA test.Among 497 couples, 12, 16, and 35 women received 1, 2, or 3 vaccination doses at baseline, respectively. Median age at vaccination was 18y. Most women (92.1%) had their first coitus before vaccination. At baseline, partner concordance of persistent HPV6/11/16/18 infections was lower in vaccinated than unvaccinated women (adjusted OR=0.10, 95%CI: 0.01-0.65) but not for non α7/α9/α10-HPV types (adjusted OR=1.00, 95%CI: 0.44-2.29). Incidence of persistent α7/α9/α10 HPV types in women was inversely associated with vaccination status at baseline (adjusted HR=0.12, 95%CI: 0.03-0.47). Likewise, male partners of vaccinated women had a lower incidence of α7/α9/α10 HPV infections (adjusted OR=0.22, 95%CI: 0.05-0.95). Vaccinated women with HPV 6/11/16/18 infections had lower viral loads (p=0.001) relative to unvaccinated women.Vaccination of sexually active women significantly reduced transmission of α7/α9/α10 HPV types in heterosexual couples.These results underscore and quantify the positive effect of HPV vaccination on HPV transmission within heterosexual couples.