Recent declines in HIV infections at Silom Community Clinic Bangkok, Thailand corresponding to HIV prevention scale up: an open cohort assessment 2005-2018.

OBJECTIVES: We assessed HIV-1 infection among men who have sex with men (MSM) attending Silom Community Clinic (SCC) in Bangkok, Thailand from 2005-2018. Since 2014, Thailand increased implementation of HIV prevention strategies including pre-exposure prophylaxis and Treatment as Prevention.

METHODS: MSM attending SCC were tested for HIV using rapid tests. We assessed trends in HIV prevalence, incidence and compared incidence before and after 2014.

RESULTS: From 2005-2018, 14,034 clients attended SCC for HIV testing. The HIV prevalence increased from 19·2% in 2005-2006 to 34·0% in 2010, remained stable until 2016 and decreased to 17·2% in 2018 (p <  0·0001). The HIV incidence was 4·1 per 100 person-years (PY), with an inverted U-shape trend and a peak in 2009 (p <  0·0001). Incidence among young MSM aged 13-21 years remained high at 10·0 per 100 PY. Among those aged 22-29 years, lower incidence was found from Q 3 2016, with a relative risk reduction of 46·2% (p <0·001); and a similar reduction among those aged ≥ 30 years from Q4 2014, corresponding to scale up of HIV prevention strategies.

CONCLUSION: We find a decline in HIV infection among MSM. However, incidence remained high among young MSM.