BACKGROUND: HIV drug resistance can reduce the effectiveness of antiretroviral drugs in preventing morbidity and mortality, limit options for treatment, and prevention. Our study aimed to assess HIV-1 subtypes and HIV drug resistance among key populations in HIV Sentinel Surveillance Plus Behavior in 2018 and 2020. METHODS: One-stage venue-based cluster sampling was used to recruit participants at hotspots identified for men who have sex with men (MSM) in 7 provinces and sexual minority females and female sex workers (FSW) in 13 provinces. Participants completed a standard questionnaire about risk and preventive behaviors, and antiretroviral therapy history, and provided intravenous blood for HIV testing. HIV drug resistance testing was conducted on HIV-positive samples with viral load >1000 copies/mL. RESULTS: A total of 185 of 435 (42.5%) HIV-positive samples had viral load ≥1000 copies/mL, of which 130 of 136 from MSM and 26 of 49 from FSW were successfully sequenced. Six HIV-1 subtypes were detected (CRF01_AE, A, CRF07/08_BC, B, C, CRF25_cpx), with CRF01_AE (82.7%, 129/156) the most common. Drug resistance mutations were detected in 16.7% of participants overall (26/156), in 15.4% (20/130) of MSM, and in 23.1% (6/26) of FSW. Mutations associated with resistance to non-nucleoside reverse transcriptase inhibitor (NNRTI) were the most frequently detected (73.1%, 19/26). The high level of resistance was presented in NNRTI and nucleoside reverse transcriptase inhibitors classes. There are 10 major resistance mutations detected with nucleoside reverse transcriptase inhibitors (M184VI-25.0%, K65KR-50.0%, Y115F-25%), NNRTI (K103N-21.1%, E138A-10.5%, V106M-5.3%, K101E-5.3%, G190A-5.3%), protease inhibitors (L33F-40.0%, M46L-20.0%). CONCLUSIONS: Vietnam's HIV Sentinel Surveillance Plus system identified an emerging strain of HIV-1 and mutations associated with resistance to multiple drug classes among MSM and FSW.

INTRODUCTION: We assessed trends in HIV and syphilis prevalence, HIV incidence, related risk factors, and preventive behaviors among men who have sex with men (MSM) in Vietnam from 2015 to 2020. METHODS: Data originated from the HIV Sentinel Surveillance Plus system, which sampled MSM at venues and hotspots in seven of Vietnam's 63 provinces in 2015, 2016, 2018, and 2020 (N = 1100-1445 per year; ∼150-300 per province per year). RESULTS: HIV prevalence estimates increased from 6.6% (95% CI 4.5-9.6) in 2015 to 13.8% (95% CI 10.5-18.2, p = .001 for trend) in 2020 overall, and separately in An Giang, Can Tho, Hai Phong, and Khanh Hoa provinces but not in Ho Chi Minh City, Hanoi, or Kien Giang. Syphilis prevalence increased from 2.7% (95% CI 1.4-5.1) in 2015 to 12.6% (95% CI 8.7-18.0) in 2020 overall (p < .001 for trend), and separately in An Giang, Can Tho, and Hai Phong provinces but not in Ho Chi Minh City or Kien Giang. We calculated time-at-risk from first anal sex to first HIV-positive or last HIV-negative test to estimate HIV incidence. Estimated HIV incidence suggested increasing rates of seroconversion from 1.36 per 100 person-years experienced by participants in 2015 to 2.61 per 100 person-years among participants in 2020 (hazard ratio per year 1.13, 95% CI 1.08-1.18, p < .001). There was a statistically significant increase in HIV testing, STI testing, and receipt of free condoms over the period (p < .05 for trend), and a statistically significant decrease in amphetamine use (p = .043 for trend). CONCLUSIONS: Despite prevention efforts and improvements in some risk indicators, consecutive cross-sectional sampling results provide evidence of increasing incidence of HIV and syphilis among MSM in Vietnam, especially outside the major cities. Aggressive HIV prevention and treatment services can be expanded while conducting deeper investigations into the causes of these increases.

To share Vietnam’s experiences piloting the integration of viral load (VL) testing into the national HIV sentinel surveillance (HSS) system to better understand the level of HIV viral transmission among people who inject drugs (PWID).