BackgroundViral hepatitis is highly prevalent among people with HIV (PWH) and can lead to chronic liver complications. Thailand started universal hepatitis B vaccination at birth in 1992 and achieved over 95% coverage in 1999. We explored the prevalence of hepatitis B and C viral infections and the associated factors among PWH from same-day antiretroviral therapy (SDART) service at the Thai Red Cross Anonymous Clinic, Bangkok, Thailand.MethodsWe collected baseline characteristics from PWH enrolled in the SDART service between July 2017 and November 2019. Multivariable logistic regression was performed to determine factors associated with positive hepatitis B surface antigen (HBsAg) and hepatitis C antibody (anti-HCV).ResultsA total of 4011 newly diagnosed PWH who had HBsAg or anti-HCV results at baseline: 2941 men who have sex with men (MSM; 73.3%), 851 heterosexuals (21.2%), 215 transgender women (TGW; 5.4%), and 4 transgender men (0.1%). Median age was 27 years. Overall seroprevalence of HBsAg and anti-HCV were 6.0 and 4.1%, respectively. Subgroup prevalence were 6.2 and 4.7% among MSM, 4.6 and 2.4% among heterosexuals, and 9.3 and 3.7% among TGW, respectively. Factors associated with HBsAg positivity were being MSM, TGW, born before 1992, CD4 count < 200 cells/mm3, and alanine aminotransferase ≥ 62.5 U/L. Factors associated with anti-HCV positivity were being MSM, age > 30 years, alanine aminotransferase ≥ 62.5 U/L, creatinine clearance < 60 ml/min, and syphilis infection.ConclusionsAround 5–10% of newly diagnosed PWH in Bangkok had hepatitis B viral infection after 25 years of universal vaccination. Anti-HCV positivity was found in 4–5% of PWH who were MSM and TGW. As World Health Organization and Thailand national guidelines already support routine screening of hepatitis B and C viral infections in PWH and populations at increased risk of HIV including MSM and TGW, healthcare providers should reinforce this strategy and provide linkage to appropriate prevention and treatment interventions. Catch-up hepatitis B vaccination should be made available under national health coverage.