Factors associated with human papillomavirus, hepatitis A, hepatitis B and mpox vaccination uptake among gay, bisexual and other men who have sex with men in the UK – findings from the large community-based RiiSH-Mpox survey

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Gay, bisexual, and other men who have sex with men (GBMSM) face a 35 disproportionate burden of sexually transmitted infections and are eligible for targeted 36 vaccinations for hepatitis A (HAV), hepatitis B (HBV), human papilloma virus (HPV) and 37 mpox. This study examines the sociodemographic characteristics, sexual behaviours, and 38 sexual healthcare service (SHS) use associated with vaccination uptake. 39

We undertook analyses of RiiSH-Mpox - an online, community-based survey with 40 GBMSM recruited via social media and dating apps. We calculated vaccination uptake (≥1 41 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. dose) among eligible GBMSM. Bivariate and multivariable logistic regression was performed 42 to identify factors independently associated with vaccination uptake among eligible 43 participants. 44

Reported uptake in eligible GBMSM was around two-thirds for each of the 45 vaccinations considered: mpox 69% (95% confidence interval (CI): 66%-72%), HAV 68% 46 (CI:65%-70%), HBV 72% (CI:69%-74%) and HPV 65% (CI:61%-68%). Vaccination course 47 completion (receiving all recommended doses) ranged from 75% (HBV) to 89% (HAV) 48 among eligible GBMSM. Individuals who represented missed opportunities for vaccination 49 ranged from 22-30% of eligible SHS attendees. Younger participants, individuals identifying 50 as bisexual, reporting lower educational qualifications, or being unemployed reported lower 51 uptake across GBMSM-selective vaccinations. Individuals who reported greater levels of 52 sexual behaviour and recent SHS use were more likely to report vaccinations. 53

Eligible participants reported high uptake of vaccinations; however, uptake was 54 lower amongst young GBMSM and self-identifying bisexual men. Awareness of groups with 55 lower vaccination uptake will help inform practice, delivery strategies and health promotion, 56 to improve the reach and impact of vaccinations amongst GBMSM. 57 Contributions: 58 DP, RW, KF, CHM, JS, HM reviewed and updated the survey instrument. Survey 59 implementation, data collection and data management were carried out by RW and DO. GB, 60 CM, DO, HM curated secondary analysis plan with review and contributions from KF, MC, 61 JS, RS, SM. GB conducted analysis and completed the first manuscript draft. All authors 62 contributed to successive drafts and reviewed and approved the final manuscript. 63 Ethics statement: 64 Ethical approval of this study was provided by the UKHSA Research and Ethics Governance 65 Group (REGG; ref: R&D 524). Online informed consent was received from all participants 66 and all methods were performed in accordance with guidelines and regulations set by the 67 UKHSA REGG. 68 Competing interests: 69 Authors have no competing interests to declare. 70 Data availability statement: 71 The data that support the findings of this study are available upon reasonable request from the 72 UK Health Security Agency (UKHSA). Requests can be directed to Dr Hamish Mohammed 73 ([email protected]). 74 Funding: 75 This study did not receive any funding and was conducted as part of the UKHSA public 76 health response to mpox. 77

78 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint The authors wish to thank all the participants who took part in this study. We acknowledge 79 members of the National Institute for Health and Care Research Health Protection Research 80 Unit (NIHR HPRU) in Blood Borne and Sexually Transmitted Infections (BBSTI) Steering 81 Committee: Professor Caroline Sabin (HPRU Director), Dr John Saunders (UK Health 82 Security Agency Lead), Professor Catherine Mercer, Dr Hamish Mohammed (previously 83 Professor Gwenda Hughes), Professor Greta Rait, Dr Ruth Simmons, Professor William 84 Rosenberg, Dr Tamyo Mbisa, Professor Rosalind Raine, Dr Sema Mandal, Dr Rosamund 85 Yu, Dr Samreen Ijaz, Dr Fabiana Lorencatto, Dr Rachel Hunter, Dr Kirsty Foster and Dr 86 Mamooma Tahir. The authors would also like to thank Takudzwa Mukiwa (Terrence Higgins 87 Trust) and Will Nutland (The Love Tank) for their review of the mpox module in the RiiSH-88 Mpox survey used for this research. 89 90 91 92 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint

93 94 95 Gay, bisexual, and other men who have sex with men (GBMSM) continue to be 96 disproportionately affected by sexually transmitted infections (STIs) and viral hepatitides 97 (VHs) both globally1 and in the UK2. To reduce individual and public health impacts of these 98 infections in the UK, several vaccines are recommended for GBMSM3–6, this includes HPV 99 (human papilloma virus), Hepatitis A (HAV) and Hepatitis B (HBV), which can be spread 100 through sexual contact amongst other means7. 101 102 UK immunisation policy and clinical advice is outlined in The Green Book: Immunisation 103 against Infectious Disease, a compilation of immunisation evidence, procedures, and 104 guidance for vaccine preventable diseases8. The UK currently recommends opportunistic 105 immunisation against HAV and HBV to all GBMSM, particularly those who change sexual 106 partners frequently3,7. HPV vaccination in the UK was initially introduced for girls aged 12-107 13 to prevent cervical cancer9, but was recommended for GBMSM up to and including age 45 108 from 2016 and for adolescent boys from 20195. Most recently, GBMSM-selective 109 vaccination programmes have been brought into focus through the rapid introduction of 110 vaccination for mpox in response to the 2022 mpox outbreak which particularly affected this 111 group10. 112 113 There is limited literature examining STI/VH vaccination uptake and acceptability among 114 GBMSM. While a pilot study among UK GBMSM found that 89% would willingly receive 115 the HPV vaccine upon recommendation11, reported uptake of the HPV vaccine is only 34% 116 among GBMSM attending sexual health services (SHS) in England (uptake has also likely 117 decreased due to the impact of COVID-19 on SHS in-person service delivery)12. Data on 118 HAV/HBV vaccination uptake among GBMSM in England is also very limited. 119 120 To understand STI/VH vaccination uptake inequalities, we investigated the factors associated 121 with uptake of recommended STI/VH vaccines in the UK among a community-sample of 122 GBMSM. 123 124

125 126 Study design and Data collection 127 128 This study used data collected by the 2022 round of the ‘Reducing inequalities in Sexual 129 Health during the mpox outbreak’ (RiiSH-mpox) survey, part of a series of cross-sectional 130 community-based surveys first run in 201713. The RiiSH surveys focus on health and 131 wellbeing, sexual risk behaviours, and use of SHS amongst GBMSM, and have been used to 132 improve understanding of the factors underlying STI trends among GBMSM in the UK14,15. 133 RiiSH-Mpox included questions on these core topics as well as mpox vaccine uptake during 134 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint the 2022 mpox outbreak. Details of the RiiSH-Mpox methodology have been previously 135 reported15. 136 137 The RiiSH-Mpox survey was deployed from 24 November-19 December 2022 and included 138 participants that were aged ≥16 years, a UK resident, individuals self-identifying as men 139 (cisgender/transgender), transgender women, or gender-diverse individuals assigned male at 140 birth (gender was overlooked in this analysis, 99% self-identified as a cis-male), and 141 individuals who self-reported having had sex with a man in the last year. Participants were 142 recruited through advertisements on social media (Facebook, Instagram, Twitter [now X]) 143 and through the geospatial networking application (‘dating app’) Grindr. Online consent was 144 provided by all participants. Lookback periods for healthcare-related factors and sexual risk 145 behaviours varied from reporting since August 2022 (i.e. last 3-4 months), to ever. 146 147 Due to relatively low numbers of participants who did not self-report being white or 148 gay/homosexual these variables were dichotomised as white or any other ethnic group, and 149 either gay/homosexual or bisexual, respectively. 150 151 Data analysis 152 153 Vaccination uptake 154 155 To measure uptake and completion levels of vaccination, percentages and 95% confidence 156 intervals (CI) (Clopper-Pearson) were calculated. Uptake was defined as receiving at least 157 one dose of a vaccine and completion as receiving all recommended doses as outlined by the 158 UK vaccination guidance at the time of the survey (2 doses of HAV, HPV or mpox vaccine 159 and 3 HBV vaccine doses). 160 161 Uptake amongst all participants and eligible GBMSM for each vaccine was calculated. 162 Reflecting UK vaccination guidance 3, we considered all GBMSM as eligible for HAV and 163 HBV vaccination. HPV vaccination eligibility was considered in GBMSM reporting SHS 164 attendance who were up to and including age 45, given opportunistic vaccination 165 recommendations across SHS. In line with mpox vaccination guidance6,10, mpox vaccination 166 eligibility was considered in those reporting: ≥10 physical male sex partners, meeting 167 partners in public sex environments (Sex on premise venues (SOP), cruising grounds or sex 168 parties), having a positive STI test, report of HIV-PrEP or use of chemsex-associated 169 recreational drugs (crystal methamphetamine, mephedrone or gamma-170 hydroxybutyrate/gamma-butyrolactone). SHS attendance was not considered as part of 171 eligibility for HAV, HBV and mpox vaccination given vaccination availability outside of 172 SHS (e.g. mpox vaccination outreach, general practice and travel clinic availability for VH 173 vaccination). 174 175 To measure the association between uptake of different vaccine types, logistic regression was 176 used to generate the unadjusted (uOR) and adjusted odds ratio (aOR) of receiving at least one 177 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint dose of a respective vaccine versus also receiving at least one dose of another vaccine 178 (vaccines were compared sequentially, in a pairwise manner). For adjusted analyses, age-179 group and sexual orientation were considered a priori, and additional factors were added in a 180 forwards stepwise manner based on significant bivariate association and evidence from 181 previous literature11,16–19. 182 183 Missed vaccination opportunities in those attending sexual health services 184 185 GBMSM who reported ever having attended an SHS and who met respective proxy 186 vaccination eligibility were considered missed opportunities for vaccination if no vaccination 187 history was reported. 188 189 Factors associated with vaccination uptake 190 191 Among all participants irrespective of previous SHS attendance (except those over age 45/ 192 those who had not previously attended SHS for HPV vaccination), Pearson’s chi-squared test 193 and bivariate logistic regression was used to examine association between sociodemographic, 194 sexual behaviour and health-related factors with vaccination uptake for the HAV, HBV and 195 HPV vaccines, respectively. Analysis of factors associated with vaccination for mpox uptake 196 has been previously reported15 so was not examined in this analysis. Multivariable adjustment 197 for significant sociodemographic, sexual behaviour and health-related factors, as per methods 198 described above, was applied. 199 200 All analysis was completed using Stata V17.0 (College Station, TX, USA) and all p values 201 below 5% were deemed statistically significant. 202 203 204

205 Altogether, 1435 individuals engaged with RiiSH-Mpox survey, of whom 1333 met the 206 inclusion criteria. Of these, half were aged over 45 years, 37% were 30-44 and the remaining 207 13% were 16-29. Almost all self-identified as gay/homosexual (89%) and were of white 208 ethnicity (92%). Most lived in England (86%), 81% were employed, 37% reported at least 209 degree level education, with 48% responding that they were financially comfortable. See 210 Appendix A for sample characteristics. 211 212 Vaccination Uptake 213 214 Among all participants, 97% self-reported receiving at least one dose of any STI/VH 215 vaccination. HAV vaccination uptake was 68% (CI:65%-70%, 903/1333) and HBV 216 vaccination was 72% (CI:69%-74, 954/1333). Mpox vaccination uptake among eligible 217 participants was 69% (CI:66%-72%, 601/875), or 52% (CI:49%-55%, 692/1,333) among all 218 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint GBMSM. In those under age 45 who had ever attended a SHS, HPV vaccination was 73% 219 (CI:69%-76%, 417/574), or 42% (CI:39%-45%, 562/1333) among all participants. 220 221 Receiving one vaccine type was uniformly associated with receiving at least one other 222 (Appendix B). The highest association was found between the HAV and HBV vaccines, 223 individuals who had received one were 12 times more likely to have received at least one 224 dose of the other (aOR:11.98, CI: 9.01-15.92). 225 226 Vaccine Completion 227 228 HAV vaccination had the highest completion level amongst participants with 89% (CI:87%-229 91%, 807/903) of those that had received at least one dose completing the course. Among 230 individuals that initiated HBV vaccination, 75% completed the course (CI:72%-77%, 231 712/954). Of those that had initiated HPV vaccination 84% (CI:80%-88%, 350/ 417) had 232 completed the course and 42% (CI:38%-45%, 288/692) of those that had initiated vaccination 233 for mpox completed the course. 234 235 Missed vaccination opportunities in those attending sexual health services 236 237 Missed vaccination opportunities among GBMSM who ever reported SHS attendance history 238 were considered 27% (CI:24-29%) for HAV vaccination, 22% (CI:20-25%) for HBV 239 vaccination, 27% (CI: 26-33%) for HPV vaccination, and 30% (CI: 26-33%) for mpox 240 vaccination. 241 242 Factors associated with vaccination uptake 243 244 Hepatitis A Vaccination uptake 245 246 There was a bivariate association between HAV uptake and sexual orientation, educational 247 level, and employment status, see Table 2. There were significantly lower odds of HAV 248 vaccination amongst those self-reporting as bisexual (aOR:0.56, (CI:0.4-0.8) vs 249 gay/homosexual), having an education that was below degree-level (aOR:0.7, (CI:0.55-0.9)) 250 and being unemployed (aOR:0.69, (CI:0.52-0.92)). There was no evidence of an independent 251 association existing between HAV vaccination uptake and age, however uptake was lower in 252 both the 16-29 age group (aOR:0.54, (CI:0.37-0.78)) and the over 45 age group (aOR:0.74, 253 (CI:0.57-0.97)). 254 255 Sexual behaviours associated with HAV vaccination uptake included self-reported usage of 256 chemsex-related recreational drugs in the previous year (aOR:1.87, (CI:1.16-3.02)), reporting 257 ten or more male physical sex partners (aOR:1.85, (CI:1.4-2.44)), reporting attendance at 258 SOP venues (aOR:1.58, (CI:1.22-2.05)), self-reporting ≥10 condomless anal sex (CAS) 259 partners (aOR:1.44, (CI:1.12-1.86)) (all since Aug 2022). Health related factors associated 260 with HAV vaccination uptake included self-reporting being a person living with HIV 261 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint (PLWHIV) (aOR:2, (CI:1.38-2.88)), receiving a positive STI test in the past year (aOR:1.95, 262 (CI:1.29-2.96)), visiting a SHS in the past year, (aOR:4.31, (CI:3.36-5.54)), STI test in the 263 past year (aOR:3.25, (CI:2.53-4.18)) and reporting usage of HIV-PrEP since December 2021 264 (aOR:3.15, (CI:2.43-4.07)). 265 266 Hepatitis B Vaccination uptake. 267 268 There was a bivariate association between HBV uptake and sexual orientation, educational 269 qualifications, and employment status, see Table 3. There were lower odds of HBV 270 vaccination uptake in those self-reporting as bisexual (aOR:0.57, (CI:0.39-0.82) vs 271 gay/homosexual), having an education that was below degree-level (aOR:0.59, (CI:0.46-272 0.76)) and being unemployed (aOR:0.71, (CI:0.53-0.96)). There was no evidence of an 273 independent association existing between HBV vaccination uptake and age however uptake 274 was lower in both the 16-29 age group (aOR:0.44, (CI:0.3-0.65)) and the over 45 age group 275 (aOR:0.53, (CI:0.4-0.7)). 276 277 Sexual behaviours associated with uptake included reported usage of chemsex-related 278 recreational drugs in the previous year (aOR:1.75, (CI:1.06-2.88)), reporting ten or more 279 physical male sex partners (aOR:1.89, (CI:1.41-2.53)) reporting attendance at SOP venues 280 (aOR:1.51, (CI:1.15-1.99)), self-reporting ≥10 CAS partners (aOR:1.77, (CI:1.37-2.29)) (all 281 since Aug 2022). There were associations with reporting being a PLWHIV (aOR:1.84, 282 (CI:1.26-2.68)), receiving a positive STI test in the past year (aOR:3.17, (CI:1.9-5.29)), 283 visiting a SHS in the past year, (aOR:5.33, (CI:4.1-6.93)), having an STI test in the past year 284 (aOR:4.29, (CI:3.31-5.58)) and reporting usage of HIV-PrEP since Dec 2021 (aOR:4.68, 285 (CI:3.51-6.26)). 286 287 288 HPV vaccination uptake 289 290 Among eligible individuals the only sociodemographic factors found to have an association 291 with HPV vaccination uptake were being in the 16-29 (younger) age-category (aOR:0.62, 292 (CI:0.43-0.89 vs those aged 30-44)) and having an education below degree-level (aOR:0.55, 293 (CI:0.39-0.78)), see Table 4. 294 295 The sexual behaviours that were associated with HPV vaccination uptake include usage of 296 chemsex-related drugs in the previous year (aOR:1.92, (CI:1.01-3.63)), reporting ten or more 297 physical male sex partners (aOR:3.85, (CI:1.77-8.37)) reporting attendance at SOP venues 298 (aOR:1.84, (CI:1.26-2.67)), self-reporting ≥10 CAS partners (aOR:4.27, (CI:2.38-7.65)) (all 299 since August 2022). There were increased odds of HPV vaccination in a multivariable model 300 amongst those reporting being a PLWHIV (aOR:3.3, (CI:1.7-6.39)), receiving a positive STI 301 test in the past year (aOR:7.77, (CI:3.5-17.28)), visiting a SHS in the past year (aOR:14.3, 302 (CI:9.51-21.51)), STI test in the past year (aOR:7.74, (CI:5.14-11.65)) and reporting usage of 303 HIV-PrEP since December 2021 (aOR:4.12, (aOR:8.99, (CI:5.97-13.53)). 304 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 305 306

307 Analyses of a large, community-based survey of GBMSM in the UK show that vaccination 308 uptake was high but far from universal for all targeted vaccinations, with uptake at around 309 two-thirds across each of the STI/VH vaccinations considered. In GBMSM attending SHS, 310 approximately a quarter were considered potential missed opportunities for vaccination 311 across each vaccine type. There was highly correlated uptake between different vaccines and 312 similar sociodemographic, behavioural and SHS use factors were associated with uptake of 313 each STI/VH vaccine. This provides an important insight into HAV, HBV and HPV 314 vaccination uptake amongst GBMSM for which there is limited uptake data in the UK21. 315 The sociodemographic factors identified in this study found to commonly be associated with 316 lower vaccination uptake were younger age, self-identifying as bisexual, and markers of 317 lower financial or social capital such as an education below degree-level or being 318 unemployed. Vaccination uptake was higher amongst those reporting sexual behaviour which 319 increases risk of STI transmission, and relatedly, in those reporting recent SHS use (greater 320 sexual behaviour is often associated with SHS utilisation20); indicating that those who are 321 most at need of vaccines are receiving them. This mirrors findings of a previous analysis of 322 mpox vaccination uptake15. Vaccine completion ranged from 42% for mpox to 89% for 323 HAV. The lower completion rate for the mpox vaccination is likely due to the recency of 324 implementation of the vaccination in response to the outbreak in 2022, as well as the fact that 325 the offer of second doses only commenced 2-3 months prior to the survey10. 326 The lower odds of vaccination amongst younger age groups has previously been reported in 327 other studies assessing HBV and HPV vaccination16,19,21. Gay self-identification, higher 328 levels of education and employment were also consistently found to be linked with higher 329 vaccination uptake amongst GBMSM, including both HBV and HPV vaccinations16,18,21. 330 Young people and bisexual/straight-identifying GBMSM have been identified as groups that 331 have a higher sexual risk and a lower SHS engagement22–24. Promotion focused on bisexual 332 men is important to reduce the burden of these vaccine preventable STI/VHs amongst 333 GBMSM, but also potentially amongst women25. 334 There is also a consistent association between higher vaccination uptake and SHS usage 335 (although HAV/HBV vaccines are also administered outside of SHS). Previous research has 336 found that GBMSM are not actively seeking out vaccines such as the HPV vaccine11,17 and 337 that vaccination for HPV is reliant on recommendation by clinicians26,27. It follows that to 338 become aware of, and to be identified as a candidate for vaccination, they must be attending 339 SHSs, (HPV vaccination is targeted to GBMSM attending SHS only). This association has 340 been identified previously with one study finding that 90.9% of GBMSM reporting HPV 341 vaccination had attended a SHS in the previous year28 (86% in this sample). 342 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 343 Those with markers of lower financial or social capital reported lower vaccination uptake, 344 indicating that health inequalities faced by GBMSM are exacerbated amongst those who 345 already experience inequity. The effects of marginalisation may be compounded, and this 346 requires an intersectional approach to understanding these groups and how to target them 347 effectively. Understanding their behaviour and whether they require changes in policy and 348 tailored interventions to increase their engagement with SHS, and subsequently uptake of 349 STI/VH vaccinations, is needed. This could be through health-promotion messaging such as 350 community outreach programmes and media-based advertisements to reach those who may 351 not normally access SHS. One means may be through encouraging online SHS29 to identify 352 potential vaccination candidates, but this does require online services that are well-integrated 353 with physical SHS and have good signposting for GBMSM, as vaccination requires 354 attendance at a physical venue. 355 Vaccine completion is also incredibly important to confer the maximum protection against 356 infection, amongst this sample many of those that initiated vaccination completed the course 357 of vaccination. One previous study assessing incomplete vaccination amongst GBMSM in 358 England found that the most common reason for not receiving additional vaccine doses was 359 because they were unaware when their next dose was due26. This indicates that vaccine 360 completion requires additional or alternative promotion to encourage that those who receive 361 their initial dose will continue to receive additional vaccine doses. 362 This study has limitations due to the cross-sectional methodology used. For example, there 363 may have been recall error as vaccination was self-reported. Also, participants’ behaviours 364 may have changed, and chronology of vaccination relative to behaviour cannot be ascertained 365 (except vaccination for mpox which only became established June 202210). There may also 366 be a degree of misclassification bias by retrospectively applying eligibility criteria to 367 participants as their behaviours may have changed over time. 368 Due to the questions regarding vaccination which fell into the ‘ever’ lookback period, it is 369 impossible to know when vaccination occurred, which could explain high association 370 between HAV and HBV vaccination due to combined packaging of the HAV and HBV 371 vaccination or administration of the combined (HAV/HBV) Twinrix vaccine. 372 There are also limitations based on the participants’ demographics with lower response 373 numbers from young people and people who did not self-describe as white. This necessitated 374 dichotomising variables, limiting the quality of these findings for minority groups who also 375 have an increased burden of STIs2,30,31, using dichotomised measures limits this study’s 376 ability to assess inequalities in vaccine access by ethnicity or gender identity. There is also 377 potential participation bias, for example the sample appears to be more health conscious than 378 the general GBMSM population. For instance, HPV vaccine uptake within the eligible 379 sample was 65% compared to 34% of GBMSM nationally12. This sample also excludes 380 GBMSM not using the applications that this survey was advertised on. However, unlike 381 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint previous studies28,32 which often focus on those attending SHS, the target population for this 382 study was the GBMSM community more broadly. 383 Improving uptake is dependent on understanding barriers faced by GBMSM which limit 384 vaccination uptake. Within the UK, awareness of factors affecting uptake (especially as the 385 JCVI has advised routine implementation of opportunistic vaccination for mpox33 and 386 gonorrhoea [the latter using 4CMenB vaccination34]), will help inform practice and health 387 promotion that aligns with NHS35 and UKHSA36 health equity goals. In an international 388 context, these results could raise awareness of potential limitations in vaccination uptake due 389 to service provision differences and sociodemographic factors in equivalent and future 390 GBMSM-selective vaccination programmes. 391 392 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint

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No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 514 n ¶ % 95% confidence interval n ¶ % 95% confidence interval n § % 95% confidence interval n †† % 95% confidence interval Mpox 692 52 49%-55% 601 69 66%-72% 252 42** 38%-46% 249 30 26-33% HAV 903 68 65%-70% 903 68 65%-70% 807 89 87%-91% 318 27 24-29% HBV 954 72 69%-74% 954 72 69%-74% 712 75 72%-77% 267 22 20-25% HPV 562 42 39%-45 429 73 69%-76% 350 84 80%-88% 157 27 24-31% Missed Opportunity †† *Uses all 1333 RiiSH-Mpox participants as a denominator † uses all eligible RiiSH-MPOX participants as a denominator, we considered all GBMSM as eligible for HAV and HBV vaccination. HPV vaccination eligibility was GBMSM reporting SHS attendance under the age of 46, mpox vaccination eligibility was considered in those reporting: ≥10 physical male sex partners, meeting partners in public sex environments (Sex on premise venues (SOP), cruising grounds or sex parties), having a positive STI test, report of PrEP or use of chemsex-associated recreational drugs (crystal methamphetamine, mephedrone or gamma-hydroxybutyrate/gamma-butyrolactone). ‡ Completion is reported as the percentage of those that received the first dose that self-reported completing the vaccine course ¶ Participants with self-reported uptake of ≥1 vaccine dose(s) § Participants with self-reported completion of that respective vaccine course, 2 doses of HAV, HPV Mpox and 3 doses of HBV ** Low completion in vaccination for Mpox may be due to recency of vaccine programme implementation ††N is all individuals who have previously attended SHS and are eligible for that particular vaccine, Mpox - 845, HA V/HBV - 1195 and HPV - 574. †† number of individuals who have not been vaccinated despite eligibility and SHS attendance. Note, for HAV and HBV vaccination uptake, the whole sample and eligible populations are the same. Whole sample * Eligible Population † Completion ‡ All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 515 n total % of RiiSH- Mpox participants n of HAV vaccinated participants * % of group vaccinated % of HAV vaccinated people uOR ** P aOR § P Sociodemographic Characteristics Age-group 16-29 176 13 101 57 11 0.48 0.34 - 0.69 0.54 0.37 - 0.78 0.570 30-44 486 36 358 74 40 1.00 1.00 45+ 671 50 444 66 49 0.70 0.54 - 0.90 0.570 0.74 0.57 - 0.97 Sexual orientation Gay/ homosexual 1187 89 823 69 91 1.00 1.00 Bisexual † 146 11 80 55 9 0.54 0.38 - 0.76 <0.001 0.56 0.40 - 0.80 0.001 Ethnicity White 1223 92 832 68 92 1.00 1.00 Other 110 8 71 65 8 0.86 0.57 - 1.29 0.454 0.90 0.59 - 1.37 0.610 Country of Birth UK 1113 83 756 68 84 1.00 1.00 Other 220 17 147 67 16 0.95 0.70 - 1.29 0.748 0.91 0.66 - 1.26 0.586 Country of Residence England 1148 86 779 68 86 1.00 1.00 Rest of UK 185 14 124 67 14 0.96 0.69 - 1.34 0.823 0.98 0.70 - 1.37 0.904 Educational level Degree level or higher 495 37 594 71 66 1.00 1.00 Below degree level 838 63 309 62 34 0.68 0.54 0.86 0.001 0.70 0.55 0.90 0.050 Employment Currently Employed 1074 19 749 70 83 1.00 1.00 Not Employed 259 81 154 59 17 0.64 0.48 - 0.84 0.002 0.69 0.52 - 0.92 0.012 Household Composition Alone 506 38 552 67 61 1.00 1.00 With Others 827 62 351 69 39 0.87 0.70 - 1.12 0.321 0.88 0.69 - 1.12 0.307 Relationship Status Relationship 591 44 510 86 56 1.00 1.00 Single 742 56 393 53 44 1.11 0.88 - 1.40 0.870 1.08 0.85 - 1.37 0.540 Comfortable Financial Status Yes †† 693 52 453 65 50 1.00 1.00 No 640 48 450 70 50 0.80 0.63 - 1.00 0.054 0.93 0.73 - 1.18 0.551 Health-related factors HIV Status Negative/ Unknown 1131 85 744 66 82 1.00 1.00 PLWHIV 202 15 159 79 18 1.92 1.34 - 2.75 <0.001 2.00 1.38 - 2.88 <0.001 MPOX-related behaviour modification ¶ No 626 47 412 66 46 1.00 1.00 Yes 707 53 491 69 54 1.18 0.94 - 1.49 0.157 1.11 0.88 - 1.42 0.355 STI Positive Test No 1177 70 778 66 86 1.00 1.00 Yes 156 30 125 80 14 3.38 2.63 - 4.35 <0.001 1.95 1.29 - 2.96 0.002 Visited SHC in past year No 478 36 221 46 24 1.00 - 1.00 - Yes 855 64 682 80 76 4.58 3.59 5.86 <0.001 4.31 3.36 5.54 <0.001 STI test in past year No 405 30 196 48 22 3.41 - 1.00 - Yes 928 70 707 76 78 1.00 2.67 4.37 <0.001 3.25 2.53 4.18 <0.001 PrEP Use in Past Year No 734 55 415 57 46 1.00 1.00 Yes 599 45 488 81 54 3.38 2.63 - 4.35 <0.001 3.15 2.43 - 4.07 <0.001 Sexual behaviours Usage of chemsex-related drugs in the previous year No 1222 92 815 67 90 1.00 1.00 Yes 111 8 88 79 10 1.91 1.19 - 3.07 0.007 1.87 1.16 - 3.02 0.010 Number of Male Physical Sex Partners none 100 8 64 64 7 1.00 1.00 1 180 14 93 52 10 0.60 0.36 - 0.99 0.59 0.35 - 0.98 <0.001 2 to 4 389 29 256 66 28 1.08 0.68 - 1.71 1.05 0.66 - 1.68 5 to 9 280 21 192 69 21 1.23 0.76 - 1.98 1.17 0.72 - 1.90 10+ 384 29 298 78 33 1.95 1.21 - 3.13 0.006 1.78 1.10 - 2.88 reported use of SOP venues in the lookback period No 888 67 568 64 63 1.00 1.00 Yes 445 33 335 75 37 1.72 1.33 - 2.21 <0.001 1.58 1.22 - 2.05 <0.001 Number of CAS partners in the lookback period (since Dec 2021) none 401 30 245 61 27 1.00 1.00 1 263 20 159 60 18 0.97 0.71 - 1.34 0.94 0.68 - 1.29 <0.001 2 to 4 315 24 219 70 24 1.45 1.06 - 1.99 1.42 1.03 - 1.95 5 to 9 146 11 118 81 13 2.68 1.70 - 4.24 2.42 1.52 - 3.85 10+ 208 16 162 78 18 2.24 1.53 - 3.29 <0.001 2.1 1.42 - 3.10 Table 2. Sociodemographic characteristics and Health-related and sexual behaviour factors associated with self-reported HAV vaccination uptake among RiiSH-Mpox participants 95% confidence interval 95% confidence interval * Participants with self-reported uptake of ≥1 HA V vaccine dose(s).† Includes those identifying as bisexual, straight, or another way. †† Top two quartiles ("I am comfortable"/"I am very comfortable" from the question, "How would you best describe your current financial situation". ¶ Behaviour modification includes self-report of any of the following from May 2022: fewer sexual partners, reduced visits to sex on premises venues or PSE (i.e. cruising grounds), and avoiding: all sex, condomless anal sex, skin-to-skin contact, or visiting clubs or crowds. § Adjusted for age-group, ethnicity, sexual orientation, educational qualifications, employment, and financial situation. ** uOR=Unadjusted odds ratio. aOR=adjusted odds ratio. All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 516 n total % of RiiSH- Mpox participants n of HBV vaccinated participants * % of group vaccinated % of HBV vaccinate d people uOR ** P aOR § P Sociodemographic Characteristics Age-group 16-29 176 13 110 63 12 0.40 0.27 - 0.58 0.44 0.30 - 0.65 0.343 30-44 486 36 392 81 41 1.00 1.00 45+ 671 50 452 67 47 0.49 0.38 - 0.65 0.343 0.53 0.40 - 0.70 Sexual orientation Gay/ homosexual 1187 89 866 73 91 1.00 1.00 Bisexual † 146 11 88 60 9 0.56 0.39 - 0.80 0.002 0.57 0.39 - 0.82 0.002 Ethnicity White 1223 92 872 71 91 1.00 1.00 Other 110 8 82 75 9 1.12 0.75 - 1.84 0.720 1.17 0.74 - 1.86 0.501 Country of Birth UK 1113 83 796 72 83 1.00 1.00 Other 220 17 158 72 17 1.01 0.74 - 1.40 0.928 0.88 0.63 - 1.24 0.469 Country of Residence England 1148 86 824 72 86 1.00 1.00 Rest of UK 185 14 130 70 14 1.01 0.74 - 1.40 0.928 0.95 0.67 - 1.35 0.770 Educational level Degree level or higher 495 37 638 76 67 1.00 1.00 Below degree level 838 63 316 64 33 0.55 0.43 0.71 <0.001 0.59 0.46 0.76 <0.001 Employment Currently Employed 1074 19 790 74 83 1.00 1.00 Not Employed 259 81 164 63 17 0.55 0.43 - 0.71 <0.001 0.71 0.53 - 0.96 0.026 Household Composition Alone 506 38 370 73 39 1.00 1.00 With Others 827 62 584 71 61 0.88 0.69 - 1.13 0.325 0.85 0.66 - 1.09 0.195 Relationship Status Relationship 591 44 539 91 56 1.00 1.00 Single 742 56 415 56 44 1.13 0.89 - 1.43 0.330 1.12 0.88 - 1.44 0.360 Comfortable Financial Status Yes †† 693 52 482 70 51 1.00 1.00 No 640 48 472 74 49 0.70 0.55 - 0.89 0.004 0.82 0.64 - 1.06 0.122 Health-related factors HIV Status Negative/ Unknown 1131 85 793 70 83 1.00 1.00 PLWHIV 202 15 161 80 17 1.67 1.16 - 2.41 0.006 1.84 1.26 - 2.68 0.001 MPOX-related behaviour modification ¶ No 626 47 434 69 45 1.00 1.00 Yes 707 53 520 74 55 1.23 0.97 - 1.56 0.088 1.14 0.90 - 1.46 0.281 STI Positive Test No 1177 70 816 69 86 1.00 1.00 Yes 156 30 138 88 14 3.39 2.04 - 5.63 <0.001 3.17 1.90 - 5.29 <0.001 Visited SHC in past year No 478 36 232 49 24 1.00 - 1.00 - Yes 855 64 722 84 76 5.76 4.45 7.45 <0.001 5.33 4.10 6.93 <0.001 STI test in past year No 405 30 198 49 21 1.00 - 1.00 - Yes 928 70 756 81 79 4.60 3.56 5.93 <0.001 4.29 3.31 5.58 <0.001 PrEP Use in Past Year No 734 55 428 58 45 1.00 1.00 Yes 599 45 526 88 55 5.15 3.87 - 0.69 <0.001 4.68 3.51 - 6.26 <0.001 Sexual behaviours Usage of chemsex-related drugs in the previous year No 1222 92 864 71 91 1.00 1.00 Yes 111 8 90 81 9 1.78 1.09 - 2.90 0.022 1.75 1.06 - 2.88 0.028 Number of Male Physical Sex Partners none 100 8 64 64 7 1.00 1.00 1 180 14 103 57 11 0.75 0.45 - 1.25 0.71 0.43 - 1.19 <0.001 2 to 4 389 29 268 69 28 1.25 0.79 - 1.98 1.16 0.72 - 1.86 5 to 9 280 21 208 74 22 1.63 1.00 - 2.65 2.51 0.92 - 2.48 10+ 384 29 311 81 33 2.40 1.48 - 3.88 <0.001 2.10 1.28 - 3.44 reported use of SOP venues in the lookback period No 888 67 606 68 64 1.00 1.00 Yes 445 33 348 78 36 1.67 1.28 - 2.18 <0.001 1.51 1.15 - 1.99 0.003 Number of CAS partners in the lookback period (since Dec 2021) none 401 30 82 20 9 1.00 1.00 1 263 20 177 67 19 1.23 0.89 - 1.71 1.19 0.85 - 1.67 0.000 2 to 4 315 24 237 75 25 1.82 1.31 - 2.52 1.83 1.31 - 2.56 5 to 9 146 11 115 79 12 2.22 1.42 - 3.46 2.02 1.28 - 3.18 10+ 208 16 174 84 18 3.06 2.01 - 4.65 0.000 2.91 1.89 - 4.47 95% confidence interval 95% confidence interval * Participants with self-reported uptake of ≥1 HBV vaccine dose(s).† Includes those identifying as bisexual, straight, or another way. †† Top two quartiles ("I am comfortable"/"I am very comfortable" from the question, "How would you best describe your current financial situation". ¶ Behaviour modification includes self-report of any of the following from May 2022: fewer sexual partners, reduced visits to sex on premises venues or PSE (i.e. cruising grounds), and avoiding: all sex, condomless anal sex, skin-to-skin contact, or visiting clubs or crowds. § Adjusted for age-group, ethnicity, sexual orientation, educational qualifications, employment, and financial situation. ** uOR=Unadjusted odds ratio. aOR=adjusted odds ratio.  Table 3. Sociodemographic characteristics and Health-related and sexual behaviour factors associated with self-reported HBV vaccination uptake among RiiSH-Mpox participants All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 517 n total % of RiiSH-Mpox participants 45+ n of HPV vaccinated participants * % of group vaccinated % of HPV vaccinated people uOR ** P aOR § P Sociodemographic Characteristics Age-group 16-29 176 27 95 54 22 0.53 0.38 - 0.760 <0.001 0.62 0.43 - 0.89 0.011 30-44 486 73 334 69 78 1.00 1.00 Sexual orientation Gay/ homosexual 579 87 385 66 90 1.00 1.00 Bisexual † 83 13 44 53 10 0.57 0.36 - 0.900 0.017 0.67 0.41 - 1.08 0.100 Ethnicity White 589 89 42 7 10 1.00 1.00 Other 73 11 387 530 90 0.71 0.43 - 1.160 0.169 0.80 0.47 - 1.35 0.399 Country of Birth UK 589 89 93 16 22 1 1.00 Other 132 20 336 255 78 1.38 0.91 - 2.080 0.130 1.32 0.85 - 2.05 0.223 Country of Residence England 565 85 367 65 86 1.00 1.00 Rest of UK 97 15 62 64 14 0.96 0.61 - 1.500 0.130 0.99 0.62 - 1.58 0.966 Educational level Degree level or higher 437 66 124 28 29 1.00 1.00 Below degree level 225 34 305 136 71 0.53 0.38 0.740 <0.001 0.55 0.39 0.78 0.001 Employment Currently Employed 572 86 385 67 90 1.00 1.00 Not Employed 90 14 44 49 10 0.47 0.30 - 0.730 0.001 0.62 0.38 - 1.00 0.051 Household Composition Alone 221 33 156 71 36 1.00 1.00 With Others 443 67 273 62 64 0.47 0.30 - 0.730 0.028 0.70 0.99 - 1.00 0.051 Relationship Status Single 343 52 213 62 50 1.00 1.00 Relationship 319 48 216 68 50 0.85 0.62 - 1.170 0.307 1.39 0.98 - 1.95 0.059 Comfortable Financial Status Yes †† 353 53 217 61 51 1.00 1.00 No 309 47 212 69 49 0.73 0.53 - 1.010 0.055 0.91 0.65 - 1.29 0.603 Health-related factors HIV Status Negative/ Unknown 584 88 363 62 85 1.00 1.00 PLWHIV 78 12 66 85 15 3.35 1.77 - 6.330 <0.001 3.30 1.70 - 6.39 0.059 MPOX-related behaviour modification ¶ No 329 50 203 62 47 1.00 1.00 Yes 333 50 226 68 53 1.31 0.95 - 1.810 0.097 1.17 0.83 - 1.64 0.368 STI Positive Test No 568 86 342 60 80 1.00 1.00 Yes 94 14 87 93 20 8.21 3.73 - 18.060 <0.001 7.77 3.50 - 17.28 <0.001 Visited SHC in past year No 227 34 62 27 14 1.00 - 1.00 - Yes 435 66 367 84 86 14.36 9.72 21.220 <0.001 14.30 9.51 21.51 <0.001 STI test in past year No 165 25 47 28 11 1.00 - 1.00 - Yes 497 75 382 77 89 8.34 9.72 21.220 <0.001 7.74 5.14 11.65 <0.001 PrEP Use in Past Year No 341 52 148 43 34 1.00 1.00 Yes 321 48 281 88 66 9.16 6.18 - 13.590 <0.001 8.99 5.97 - 13.53 <0.001 Sexual behaviours Usage of chemsex-related drugs in the previous year No 601 91 382 64 89 1.00 1.00 Yes 61 9 47 77 11 1.93 1.04 - 3.580 0.038 1.92 1.01 - 3.63 0.047 Number of Male Physical Sex Partners None 34 5 16 47 4 1.00 1.00 1 88 13 39 44 9 0.90 0.41 - 1.98 0.85 0.38 - 1.92 <0.001 2 to 4 200 30 120 60 28 1.69 0.81 - 3.50 1.63 0.77 - 3.46 5 to 9 135 20 90 67 21 2.25 1.05 - 4.82 2.12 0.97 - 4.63 10+ 205 31 164 80 38 4.50 2.11 - 9.58 3.85 1.77 - 8.37 reported use of SOP venues in the lookback period No 442 67 262 59 61 1.00 1.00 Yes 220 33 167 76 39 2.17 1.51 - 3.11 <0.001 1.84 1.26 - 2.67 0.001 Number of CAS partners in the lookback period (since Dec 2021) None 172 26 87 51 20 1.00 1.00 1 138 21 74 54 17 1.13 0.72 - 1.77 1.03 0.65 - 1.64 <0.001 2 to 4 157 24 110 70 26 2.29 1.45 - 3.60 2.19 1.37 - 3.50 5 to 9 74 11 57 77 13 2.28 1.77 - 6.08 2.74 1.45 - 5.16 10+ 121 18 101 83 24 4.93 2.80 - 8.68 <0.001 4.27 2.38 - 7.65 95% confidence interval 95% confidence interval * Participants with self-reported uptake of ≥1 HPV vaccine dose(s) in those under 45 years.† Includes those identifying as bisexual, straight, or another way. †† Top two quartiles ("I am comfortable"/"I am very comfortable" from the question, "How would you best describe your current financial situation". ¶ Behaviour modification includes self-report of any of the following from May 2022: fewer sexual partners, reduced visits to sex on premises venues or PSE (i.e. cruising grounds), and avoiding: all sex, condomless anal sex, skin-to-skin contact, or visiting clubs or crowds. § Adjusted for age-group, ethnicity, sexual orientation, educational qualifications, employment, and financial situation. ** uOR=Unadjusted odds ratio. aOR=adjusted odds ratio.  Table 4. Sociodemographic characteristics and Health-related and sexual behaviour factors associated with self-reported HPV vaccination uptake among RiiSH-Mpox participants below 45 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 518 n total % of RiiSH- Mpox participants n of mpox vaccinated participants % of MPOX vaccinated people n of HAV vaccinated participants % of HAV vaccinated people n of HBV vaccinated participants % of HBV vaccinated people n of HPV vaccinated participants % of HPV vaccinated people Sociodemographic Characteristics Age-group 16-29 176 13 78 11 101 11 110 12 95 17 30-44 486 36 263 38 358 40 392 41 334 59 45+ 671 50 351 51 444 49 452 47 133 24 Sexual orientation Gay/ homosexual 1187 89 645 93 823 91 866 91 509 91 Bisexual * 146 11 47 7 80 9 88 9 53 9 Ethnicity White 1223 92 635 92 832 92 872 91 512 91 Other 110 8 57 8 71 8 82 9 50 9 Country of Birth UK 1113 83 566 82 756 84 796 83 446 79 Other 220 17 126 18 147 16 158 17 116 21 Country of Residence England 1148 86 613 89 779 86 824 86 479 85 Rest of UK 185 14 79 11 124 14 130 14 83 15 Educational level Degree level or higher 838 63 199 29 594 66 638 67 394 70 Below degree level 495 37 493 71 309 34 316 33 169 30 Employment Currently Employed 1074 19 595 86 749 83 790 83 497 88 Not employed 259 81 97 14 154 17 164 17 65 12 Household Composition With others 827 38 515 74 351 39 584 61 342 61 Alone 506 62 278 40 552 61 370 39 220 39 Relationship Status In relationship 591 44 320 46 510 56 539 56 291 52 Single 742 56 372 54 393 44 415 44 271 48 Comfortable Financial Status Yes 693 52 331 48 453 50 482 51 282 50 No 640 48 361 52 450 50 472 49 280 50 Sexual behaviours Usage of chemsex-related drugs in the previous year No 1222 92 617 89 815 90 864 91 500 89 Yes 111 8 75 11 88 10 90 9 62 11 Number of Male Physical Sex Partners None 100 8 31 4 64 7 64 7 28 5 1 180 14 41 6 93 10 103 11 47 8 2 to 4 389 29 170 25 256 28 268 28 159 28 5 to 9 280 21 180 26 192 21 208 22 119 21 10+ 384 29 270 39 298 33 311 33 209 37 reported use of SOP venues in the lookback period No 888 67 382 55 568 63 606 64 346 62 Yes 445 33 310 45 335 37 348 36 216 38 Number of CAS partners in the lookback period None 401 30 57 8 245 27 82 9 119 21 1 263 20 99 14 159 18 177 19 96 17 2 to 4 315 24 185 27 219 24 237 25 143 25 5 to 9 146 11 109 16 118 13 115 12 78 14 10+ 208 16 143 21 162 18 174 18 126 22 Health-related factors HIV Status Negative/ Unknown 1131 85 575 83 744 82 793 83 461 82 PLWHIV 202 15 117 17 159 18 161 17 101 18 MPOX-related behaviour modification † † No 626 47 247 36 412 46 434 45 264 47 Yes 707 53 445 64 491 54 520 55 298 53 STI Positive Test No 1177 70 568 82 778 86 816 86 457 81 Yes 156 30 124 18 125 14 138 14 105 19 Visited SHC in past year No 478 36 82 12 221 24 232 24 60 11 Yes 855 64 610 88 682 76 722 76 484 86 STI test in past year No 405 30 81 12 196 22 198 21 60 11 Yes 928 70 611 88 707 78 756 79 502 89 PrEP Use in Past Year No 734 55 228 33 415 46 428 45 201 36 Yes 599 45 464 67 488 54 526 55 361 64 Appendix A. Sociodemographic, Health-related and sexual behaviour characteristics of those who self-reported ≥1 dose of the Mpox, HAV, HBV and HPV vaccines amongst RiiSH-Mpox participants * also includes those identifying straight, or another way. . † Top two quartiles ("I am comfortable"/"I am very comfortable" from the question, "How would you best describe your current financial situation". †† Behaviour modification includes self-report of any of the following: fewer sexual partners, reduced visits to sex on premises venues or PSE and avoiding: all sex, condomless anal sex, skin-to-skin contact, or visiting clubs or crowds from May 2022.  All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint 519 n n receiving both vaccines * % receiving both vaccines uOR † P aOR † † P Any Vaccine Uptake 1135 97 Mpox Vaccine uptake Mpox 692 HAV 903 558 62 3.57 2.80 - 4.56 <0.001 3.30 2.57 - 4.25 <0.001 HBV 954 581 61 3.76 2.91 - 4.86 <0.001 3.40 2.61 - 4.42 <0.001 HPV 562 387 69 3.38 2.69 - 4.25 <0.001 4.14 3.16 - 5.42 <0.001 HAV Vaccine Uptake 903 68 Mpox 692 558 81 3.57 2.80 - 4.56 <0.001 3.30 2.57 - 4.25 <0.001 HAV 903 HBV 954 794 83 12.29 9.29 - 16.26 <0.001 11.98 9.01 - 15.92 <0.001 HPV 562 490 87 5.90 4.44 - 7.84 <0.001 8.04 5.82 - 11.11 <0.001 HBV Vaccine uptake 954 72 Mpox 692 581 84 3.76 2.91 - 4.86 <0.001 3.40 2.61 - 4.42 <0.001 HAV 903 794 88 12.29 9.29 - 16.26 <0.001 11.98 9.01 - 15.92 <0.001 HBV 954 HPV 562 512 91 7.62 5.15 - 10.53 <0.001 9.27 6.51 - 13.21 <0.001 HPV Vaccine Uptake 42 Mpox 692 387 56 3.38 2.69 - 4.25 <0.001 3.30 2.57 - 4.25 <0.001 HAV 903 490 54 5.90 4.44 - 7.84 <0.001 8.04 5.82 - 11.11 <0.001 HBV 954 512 54 7.62 5.52 - 10.53 <0.001 9.27 6.51 - 13.21 <0.001 HPV 562 Appendix B Vaccine uptake and association between uptake of different STI vaccine types amongst RiiSH-Mpox participants 95% confidence interval 95% confidence interval * Participants with self-reported uptake of ≥1 vaccine dose of both vaccine types.† uOR=Unadjusted odds ratio. aOR=adjusted odds ratio. † † Adjusted for age- group, sexual orientation, educational level, employment, ethnicity and financial situation. All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for thisthis version posted March 10, 2024. ; https://doi.org/10.1101/2024.03.08.24303981doi: medRxiv preprint