Prevalence and associated risk factors of anal high-risk human papillomavirus infection in unvaccinated young men who have sex with men visiting the Center of Sexual Health of Amsterdam

Background: Anal high-risk human papillomavirus (hrHPV) is highly prevalent among men who have sex with men (MSM) and the main cause of anal cancer. The effectiveness of HPV vaccination in this population is highly dependent on prior HPV exposure. We aimed to assess the prevalence and determinants of anal hrHPV among young unvaccinated MSM attending the Center for Sexual Health (CSH) of Amsterdam. These findings will serve as a basis for analyses regarding the prophylactic effectiveness and population impact of HPV vaccination among MSM in the Netherlands. Methods: All unvaccinated MSM aged 19–28 years visiting the CSH of Amsterdam during the National 2023-2024 HPV catch-up campaign were eligible. Participants provided socio-demographic and sexual behaviour information, a venous blood sample and anal self-sample. Samples were tested for HPV, HIV, chlamydia, gonorrhoea, and syphilis. HPV DNA-positive anal samples were genotyped using the SPF10 DEIA/LiPA-25 system. Determinants of hrHPV positivity and HPV16/18 were examined using multivariable logistic regression with generalized estimating equations. Results: Among 431 MSM (median age 24 years), 51.0% tested positive for any anal hrHPV-type, 14.6% for HPV16 and 8.1% for HPV18. In multivariable analyses, lifetime number of sexual partners (adjusted odds ratio [aOR] per natural log increase: 1.33, 95%CI 1.16–1.51), inconsistent versus consistent condom use during receptive anal intercourse (aOR 1.68, 95%CI 1.02–2.76) and anal gonorrhoea (aOR 1.51, 95%CI 1.00-2.29) were associated with hrHPV positivity. Conclusions: Prevalence of hrHPV among young unvaccinated MSM is high and associated with sexual behaviours and inconsistent condom use.