HIV testing among men who have sex with men (MSM) and transgender (TG) women remains low in Thailand. The HIV prevention program (PREV) to increase HIV testing and link those who tested HIV-positive to care provided trainings to peer educators to conduct target mapping, identify high risk MSM and TG women through outreach education and offer them rapid HIV testing. Trained hospital staff provided HIV testing and counseling with same-day results at hospitals and mobile clinics and referred HIV-positive participants for care and treatment. We used a standardized HIV pre-test counseling form to collect participant characteristics and analyzed HIV test results using Poisson regression and Wilcoxon rank sum trend tests to determine trends over time. We calculated HIV incidence using data from participants who initially tested HIV-negative and tested at least one more time during the program. Confidence intervals for HIV incidence rates were calculated using the Exact Poisson method. From September 2011 through August 2016, 5,629 participants had an HIV test; their median age was 24 years, 1,923 (34%) tested at mobile clinics, 5,609 (99.6%) received their test result, and 1,193 (21%) tested HIV positive. The number of people testing increased from 458 in 2012 to 1,832 in 2016 (p < 0.001). Participants testing at mobile clinics were younger (p < 0.001) and more likely to be testing for the first time (p < 0.001) than those tested at hospitals. Of 1,193 HIV-positive participants, 756 (63%) had CD4 testing. Among 925 participants who returned for HIV testing, HIV incidence was 6.2 per 100 person-years. Incidence was highest among people 20-24 years old (10.9 per 100 person-years). HIV testing among MSM and TG women increased during the PREV program. HIV incidence remains alarmingly high especially among young participants. There is an urgent need to expand HIV prevention services to MSM and TG women in Thailand.

The HIV epidemic in Thailand is concentrated in key populations, with the highest rates in men who have sex with men (MSM) and transgender women (TG). Previous studies of HIV incidence in these groups have been limited mostly to Bangkok. We measured HIV incidence in MSM and TG in four provinces and evaluated factors associated with incident infections to inform public health prevention efforts. An analysis was conducted using data collected during a prospective observational cohort study during April 2015–May 2018 in outpatient clinics in five hospitals across four provinces in Thailand. MSM and TG aged ≥18 years, who were not known to be HIV-infected, and who reported anal intercourse with a male or TG without a condom in the past six months were enrolled. Participants were followed-up every 6 months for 18 months with questionnaires and HIV testing. A total of 40 HIV seroconversions occurred during follow-up, resulting in an HIV incidence of 3.5 per 100 person-years (95% CI 2.5, 4.8). Multivariate analyses indicated that identifying as gay (adjusted hazard ratio [AHR] 4.9; 95% CI 1.7–14.2), having receptive anal sex in the past six months (AHR 3.6; 95% CI 1.4–9.5), using alcohol (AHR 3.3; 95% CI 1.3–8.3), and taking alkyl nitrites (AHR 4.4; 95% CI 1.7–11.2) in the past six months were all independently associated with HIV infection. Overall this study found a lower HIV incidence in the highest risk population in Thailand compared with similar studies in Bangkok. Accelerated prevention efforts are needed to make the goal of ‘zero new infections’ possible in Thailand.