Anal Human Papillomavirus Prevalence Among Vaccinated and Unvaccinated Gay, Bisexual, and Other Men Who Have Sex With Men in Canada.

Background: Starting in 2015, human papillomavirus (HPV) vaccine has been publicly funded for gay, bisexual, and other men who have sex with men (GBM) 26 years or younger in Canada.

Methods: Self-identified GBM who reported having sex with another man within the past 6 months were enrolled using respondent-driven sampling (RDS) between February 2017 and August 2019 in Montreal, Toronto, and Vancouver, Canada. Men aged 16 to 30 years self-collected anal specimens for HPV-DNA testing. Prevalence was estimated using RDS-II weights. We compared the prevalence of quadrivalent (HPV-6/11/16/18) and 9-valent (HPV-6/11/16/18/31/33/45/52/58) vaccine types between GBM who self-reported HPV vaccination (≥1 dose) and those reporting no vaccination using a modified Poisson regression for binary outcomes.

Results: Among 645 GBM who provided a valid anal specimen (median age, 26 years; 5.9% HIV positive), 40.3% reported receiving ≥1 dose of HPV vaccine, of whom 61.8% received 3 doses. One-quarter were infected with ≥1 quadrivalent type (crude, 25.7%; RDS weighted, 24.4%). After adjustment for potential confounders, vaccinated GBM had a 27% lower anal prevalence of quadrivalent types compared with unvaccinated GBM (adjusted prevalence ratio [aPR], 0.73; 95% confidence interval [CI], 0.54-1.00). Lower prevalence ratios were found among vaccinated participants who were vaccinated >2 years before enrollment (aPR, 0.47; 95% CI, 0.25-0.86) or received their first vaccine dose at age ≤23 years (aPR, 0.64; 95% CI, 0.42-0.99). Point estimates were similar for ≥2 or 3 doses and 9-valent types.

Conclusions: Human papillomavirus vaccination was associated with a lower anal prevalence of vaccine-preventable HPV types among young, sexually active GBM. Findings will help inform shared decision making around HPV vaccination for GBM and their healthcare providers.