Increases in both HIV and syphilis among men who have sex with men in Vietnam: Urgent need for comprehensive responses.

The objective of this study was to determine the temporal trends and factors associated with HIV and syphilis infection among men who have sex with men (MSM) in southern Vietnam. Data from the 2014-2018 national HIV sentinel surveillance of MSM aged 16 years or older were collected from three provinces, including An Giang ( = 761), Can Tho ( = 900), and Ho Chi Minh City ( = 1426), and examined for changes in prevalence rates of HIV and syphilis and risk behaviors over time. Multivariate logistic regression was performed to assess the trends and correlates of HIV and syphilis infections among MSM. There were upward trends for HIV (9.5% in 2014 to 14.2% in 2018, p-trend<0.01), syphilis (4.9% in 2014 to 8.0% 2018, p-trend<0.01), and HIV/syphilis co-infection (1.9% in 2014 to 3.1% in 2018, p-trend=0.01). Factors associated with HIV infection included place of residence, early sexual debut, consistent condom use and not engaging in anal sex during the past month, not knowing one's HIV test results, having ever injected drugs, and having active syphilis. Additionally, early sexual debut and being HIV positive were associated with syphilis infection. Rising prevalences of these infections among MSM suggests an urgent need for comprehensive intervention packages for HIV/STI prevention.