van Santen DK, et al. - The frequency of delayed hepatitis B surface antigen (HBsAg)-seroclearance, along with its determinants, was examined among people who use drugs (PWUD) and men who have sex with men (MSM). Further, they sought for time to delayed HBsAg-seroclearance among these adult high-risk groups. Researchers obtained data of MSM and PWUD enrolled in the Amsterdam Cohort Studies (1985-2002) who had anti-hepatitis B core antibody seroconversion. They identified the occurrence of 147 incident hepatitis B virus (HBV)-infections during follow-up. The analysis revealed a common occurrence of delayed HBsAg-seroclearance in these key adult populations at-risk for HBV, while HBV chronicity develop in still higher proportion (18%) is these populations compared to the general population (~5%). They suggest performing HBV-DNA testing in HCV co-infected MSM/PWUD prior to treatment initiation in view of the proportion of individuals with occult HBV-infection and the possibility for HBV reactivation following HCV direct-acting antivirals.