BackgroundGay, bisexual, and other men who have sex with men (GBMSM) face a disproportionate burden of sexually transmitted infections and are eligible for targeted vaccinations for hepatitis A (HAV), hepatitis B (HBV), human papilloma virus (HPV) and mpox. This study examines the sociodemographic characteristics, sexual behaviours, and sexual healthcare service (SHS) use associated with vaccination uptake.MethodsWe undertook analyses of RiiSH-Mpox - an online, community-based survey with GBMSM recruited via social media and dating apps. We calculated vaccination uptake (≥1 dose) among eligible GBMSM. Bivariate and multivariable logistic regression was performed to identify factors independently associated with vaccination uptake among eligible participants.ResultsReported uptake in eligible GBMSM was around two-thirds for each of the vaccinations considered: mpox 69% (95% confidence interval (CI): 66%-72%), HAV 68% (CI:65%-70%), HBV 72% (CI:69%-74%) and HPV 65% (CI:61%-68%). Vaccination course completion (receiving all recommended doses) ranged from 75% (HBV) to 89% (HAV) among eligible GBMSM. Individuals who represented missed opportunities for vaccination ranged from 22-30% of eligible SHS attendees. Younger participants, individuals identifying as bisexual, reporting lower educational qualifications, or being unemployed reported lower uptake across GBMSM-selective vaccinations. Individuals who reported greater levels of sexual behaviour and recent SHS use were more likely to report vaccinations.ConclusionEligible participants reported high uptake of vaccinations; however, uptake was lower amongst young GBMSM and self-identifying bisexual men. Awareness of groups with lower vaccination uptake will help inform practice, delivery strategies and health promotion, to improve the reach and impact of vaccinations amongst GBMSM.ContributionsDP, RW, KF, CHM, JS, HM reviewed and updated the survey instrument. Survey implementation, data collection and data management were carried out by RW and DO. GB, CM, DO, HM curated secondary analysis plan with review and contributions from KF, MC, JS, RS, SM. GB conducted analysis and completed the first manuscript draft. All authors contributed to successive drafts and reviewed and approved the final manuscript.Ethics statementEthical approval of this study was provided by the UKHSA Research and Ethics Governance Group (REGG; ref: R&D 524). Online informed consent was received from all participants and all methods were performed in accordance with guidelines and regulations set by the UKHSA REGG.Competing interestsAuthors have no competing interests to declare.Data availability statementThe data that support the findings of this study are available upon reasonable request from the UK Health Security Agency (UKHSA). Requests can be directed to Dr Hamish Mohammed (hamish.mohammed@ukhsa.gov.uk).FundingThis study did not receive any funding and was conducted as part of the UKHSA public health response to mpox.