Ongoing susceptibility to hepatitis B virus infection among people who inject drugs in Sydney

Abstract Objective: To determine hepatitus B virus (HBV) vaccine‐induced immunity and infection in people who inject drugs (PWID) screened for a prospective observational study in Sydney. Method: 227 PWID completed a brief demographic and risk behaviour survey and provided blood for HBV, hepatitis C virus antibody (anti‐HCV) and HIV testing. Correlates of HBV status were examined in the overall sample and HBV protective immunity was assessed in a subset of anti‐HCV negative participants (n=124); a population with typically shorter injecting histories but at potentially high risk for HBV and HCV. Results: Almost half (45%) were susceptible to HBV infection. Only 84 (37%) had evidence of vaccine‐induced immunity (HBV surface antibody ≥10 mLU/mL and HBV core antibody (anti‐HBc) negative) and 40 (18%) tested anti‐HBc positive, of whom 7 (4%) were also HBV surface antigen positive. HBV vaccine‐induced immunity was associated with a history of incarceration (AOR 1.98; 95% CI 1.05–3.71, p=0.034) while HBV infection was associated with prior HCV infection (AOR 6.29; 95% CI 2.29–17.24, p