Human Papillomavirus Vaccine Effectiveness by Age, Age at Vaccination, and Timing of Vaccination Relative to Age at First Sex Among Men Who Have Sex With Men-Seattle, Washington, 2018 to 2020.

Background: We evaluated human papillomavirus (HPV) vaccine effectiveness (VE) against prevalent anal HPV among men who have sex with men (MSM) by age, age at vaccination, and age at vaccination relative to age at first sex.

Methods: Residual anal specimens from 1092 MSM aged 18 to 45 years attending a Seattle, Washington, sexual health clinic in 2018 to 2020 were tested for 28 HPV types. Demographic, clinical, sexual behavioral, and HPV vaccination data were extracted from clinic and electronic medical records. We calculated adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) for associations between vaccination (≥1 dose of any HPV vaccine) and quadrivalent HPV vaccine (4vHPV)-type infection, by age group (18-26, 27-35, 36-45 years), vaccination age (among age groups 18-26, 27-35 years), and vaccination age relative to first sex (among those 18-26 years). Analyses were adjusted for race and ethnicity, preexposure prophylaxis use for HIV prevention, and lifetime number of sex partners. Vaccine effectiveness was calculated as (1 - aPR) × 100.

Results: Among persons aged 18 to 26 years, 4vHPV-type HPV prevalence was lower among those vaccinated before first sex (aPR, 0.12 [95% CI, 0.02-0.87]; VE, 88%) or at <18 years of age (aPR, 0.22 [95% CI, 0.07-0.68]; VE, 78%) versus unvaccinated, but no VE was observed in those vaccinated at 18 to 26 years of age. Among persons aged 27 to 35 years, 4vHPV-type HPV prevalence was lower among those vaccinated at 18 to 26 years of age versus unvaccinated (aPR, 0.56 [95% CI, 0.36-0.87]; VE, 44%). No VE was observed in persons aged 27 to 35 or 36 to 45 years who were vaccinated at >26 years of age.

Conclusions: Results highlight the importance of routine HPV vaccination in adolescence and support efforts to increase catch-up vaccination among MSM.