KUAN-YIN LINLai, Shuo-LunShuo-LunLaiYU-SHAN HUANGHSIN-YUN SUNYU-CHUNG CHUANGLiu, Wen-ChunWen-ChunLiuI-SHIOW JANCHIEN-CHING HUNGCHI-TAI FANG2026-02-262026-02-262026-12https://scholars.lib.ntu.edu.tw/handle/123456789/736009Men who have sex with men (MSM) with HIV are disproportionately affected by persistent human papillomavirus (HPV) infections and related anogenital cancers. No controlled trial has evaluated the efficacy of the nonavalent HPV vaccine (9vHPV) in this population. This prospective, controlled cohort study offered eligible MSM with HIV a 3-dose 9vHPV series and followed both the vaccinated group (vaccinees) and the unvaccinated group (controls). Anal specimens were collected for HPV genotyping, cytology, and microbiota profiling. The primary outcomes were the clearance and incidence of 9vHPV-covered HPV types. Baseline vaccine-type HPV prevalence was 41.0% in vaccinees (n = 39; median age, 33 y; median CD4, 682/μl) and 39.3% in controls (n = 56; median age, 35 y; median CD4, 679/μl) ( = .865). At month 3, 75.0% of vaccinees with prevalent HPV infection had cleared at least one genotype, and 85.7% of those with abnormal baseline cytology experienced regression. However, clearance rates (per 1000 person-months) were 46.3 (vaccine type) and 56.0 (non-vaccine type) in vaccinees versus 64.1 and 91.8 in controls ( = .456 and 0.371). HPV incidence was 19.5 (vaccine type) and 15.1 (non-vaccine type) in vaccinees versus 12.4 and 12.4 in controls ( = .378 and 0.710). 9vHPV vaccination was not associated with enhanced clearance (aHR, 0.27; 95% CI, 0.11-0.68) or decreased incidence of vaccine-type HPV (aHR, 0.44; 95% CI, 0.11-1.82). No significant differences were observed in anal dysplasia regression or anal microbiota composition over 12 months. Given the lack of short-term secondary benefit and persistence of HPV incidence, MSM with HIV require continued routine anal cancer screening.enClearanceanal cancer screeninganal cytologymicrobiotaprecancerous lesionregressionsexually transmitted infectionjournal article10.1080/21645515.2026.261887641586588