Doxycycline prophylaxis for sexually transmitted infection prevention in Vietnam: Awareness, attitudes, and willingness to use among men who have sex with men using HIV-PrEP.

Objectives: Doxycycline prophylaxis shows promise for sexually transmitted infection (STI) prevention, but data primarily come from high-income countries. This study assessed awareness, willingness and factors associated with willingness to use doxycycline for STI prevention among men who have sex with men (MSM) using HIV-PrEP in Vietnam. Methods: Between January 25 and February 4, 2024, a cross-sectional study recruited males aged ≥18 years who reported sex with men in the past 12 months from 11 PrEP clinics in Hanoi and Ho Chi Minh City. Self -administered surveys were conducted, and multivariable logistic regression was applied to identify factors associated with willingness to use doxyPEP/PrEP. Results: Among 350 participants (45.7% Hanoi, 54.3% Ho Chi Minh City), the median age was 25 (interquartile range [IQR]: 21-30), and 10.6% self-reported an STI diagnosis in the past 12 months. In the previous 6 months, the median number of sex partners was 2 (IQR: 1-4), 53.1% reported condomless anal sex. Awareness of doxycycline was low (20.2%; 65/322), however, 75.4% (264/350) expressed willingness to use it, with 63.6% (168/264) preferring doxyPrEP. Participants who disclosed HIV-PrEP use to all sex partners (adjusted odds ratio [aOR]: 4.17; 95% confidence interval [95%CI] 1.84, 9.46), and those with higher perceived STI risk (aOR: 1.12; 95% CI 1.03, 1.22) were more likely to report willingness to use doxycycline prophylaxis. Concerns about daily medication (aOR: 0.43; 95% CI 0.24, 0.81) and fear of judgement from peers (aOR: 0.41; 95% CI: 0.21, 0.81) were associated with lower willingness. Conclusions: Knowledge of doxyPEP/PrEP among MSM on HIV-PrEP in Vietnam was low. However, most expressed willingness to use doxycycline prophylaxis, with two-thirds preferring doxyPrEP. Findings highlight the need to disseminate information on doxyPEP/PrEP for STI prevention strategy, evaluating the usage and comparative effectiveness of doxyPEP and doxyPrEP to guide implementation efforts in Vietnam. 1 What is already known on this topic: Men who have sex with men (MSM) experience a disproportionate burden of HIV and bacterial sexually transmitted infections (STIs) worldwide, including in Vietnam. Despite the successful expansion of HIV Pre-Exposure Prophylaxis (PrEP) programs in Vietnam, bacterial STI rates remain persistently high among PrEP users, highlighting gaps in prevention efforts. Evidence from high-income countries (HICs) suggests that doxycycline prophylaxis can significantly reduce the incidence of bacterial STIs such as syphilis and chlamydia. However, little is known about the awareness, acceptability, and feasibility of doxycycline prophylaxis in Vietnam and other low-and middle-income countries (LMICs). 2 What this study adds: This study is the first to assess awareness, attitudes, and willingness to use doxycycline prophylaxis for STI prevention among MSM in Vietnam, a LMIC setting. Despite low prior awareness, the study found high willingness (75.4%) to use doxycycline, with most participants preferring daily doxyPrEP over doxyPEP. It also identified critical facilitators, such as perceived high STI risk and disclosure of HIV-PrEP use to sex partners, as well as barriers, including stigma, cost, and concerns about daily medication. These findings provide insights into the feasibility of introducing doxycycline prophylaxis in Vietnam, distinguishing it from contexts in HICs where different preferences and barriers may exist. 3 How this study might affect research practice or policy: This study provides a foundation for further research on doxycycline prophylaxis in LMICs, emphasizing the need to evaluate its real-world effectiveness and implementation in settings with high AMR prevalence. Policymakers can use these findings to develop tailored guidelines and subsidies for doxycycline prophylaxis in Vietnam, ensuring affordability and accessibility.