amfAR, The Foundation for AIDS Research

Sex Among MSM in Bangkok: Implications for Pre-exposure Prophylaxis


October 2010—Several clinical trials are under way among men who have sex with men (MSM) to evaluate the safety and effectiveness of pre-exposure prophylaxis (PrEP)—giving antiretroviral (ARV) drugs to HIV-negative people to prevent HIV infection. Trial interventions include a daily or intermittent oral dose of the ARV tenofovir, or a combination of tenofovir and emtricitabine.1 But it is not clear if PrEP—whether daily or intermittent—would be a feasible prevention strategy in resource-limited settings in Asia.

A recent study of HIV-negative MSM in Bangkok evaluated factors that would influence the effectiveness of taking prophylactic ARVs, including the frequency of sex, whether it is planned or unplanned, and the likelihood of exposure to HIV. Among 823 men from the Bangkok MSM Cohort Study, 64 percent had sex less than once a week, 18 percent several times a week, and 1.3 percent every day.2 Sex was more frequent on Saturday and Sunday than on other days of the week. Among participants who had had sex in the previous week, 66 percent reported that it had been planned. Alcohol use in the past four months, use of erectile dysfunction drugs, group sex, sex with a foreigner, buying or selling sex, and a history of HIV testing were associated with having sex three or more days a week. Being 22 to 29 years old, not identifying as homosexual, having receptive anal sex, having lower formal education, and not engaging in group sex were associated with unplanned sex.2

The study authors suggested that intermittent PrEP (iPrEP) may be a more suitable approach than daily PrEP for most of the men who participated in the survey. This study may assist in informing the development of iPrEP trials for MSM in Thailand.

1. AVAC. PrEP Trials Table March 2010. Available:

2. van Griensven F, et al. Sex frequency and sex planning among men who have sex with men in Bangkok, Thailand: implications for pre- and post-exposure prophylaxis against HIV infection. Journal of the International AIDS Society. 2010; 13: 1–15.