Doxycycline post-exposure prophylaxis among men who have sex with men and transgender women in Belgium: awareness, use, and antimicrobial resistance concerns in a cross-sectional online survey

Objectives We aimed to assess the awareness, willingness to use, and actual use of doxycycline post-exposure prophylaxis (doxyPEP) among men who have sex with men (MSM) and transgender women (TGW) in Belgium. Additionally, we aimed to identify factors associated with doxyPEP use and concerns regarding antimicrobial resistance (AMR). Methods Cross-sectional online survey among MSM and TGW in Belgium in April 2024. Participants were recruited through sexual networking applications and social media of community-based organizations. Numerical variables were compared with Wilcoxon rank-sum test and categorical variables with chi-square or Fisher s exact tests. Factors associated with doxyPEP use were assessed using logistic regression. Willingness to use doxyPEP and concerns about side-effects/AMR were assessed before and after presenting a brief paragraph on the potential effects of doxyPEP on AMR. Results A total of 875 individuals initiated the survey. Almost all identified as men (860/875, 98.3%) with a median age of 40 years (IQR 32-48). Among all respondents, 40.4% (n=352/875) had heard of doxyPEP and 9.4% (n=82/875) had used it, among whom the majority used it within the last six months (70/81, 86.4%). In multivariable logistic regression, doxyPEP use was associated with having had [≥]1 STI in the past 12 months and engagement in chemsex. About 80% of the participants initially reported being willing to use doxyPEP, and about 50% reported being concerned about side effects. After reading about the potential effects of doxyPEP on AMR, willingness to use doxyPEP decreased to 60% and concerns of side-effects including AMR increased to around 70%. Conclusions Approximately one in ten MSM and TGW in Belgium reported using doxyPEP, with those at highest STI risk reporting higher usage. Importantly, concerns about AMR and side effect influenced willingness to use doxyPEP. If doxyPEP is introduced, informing patients about doxyPEP benefits and risks is crucial to enable informed decision-making.