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

Abstract

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<0.001). Among anti‐HCV negative participants, HBV vaccine‐induced immunity was significantly lower among those who reported lifetime receptive syringe sharing (AOR 0.38; 95% CI 0.15–0.95, p=0.04). Conclusions: Low HBV vaccine coverage among PWID suggests that improved efforts to increase vaccination uptake and completion are still required as those of greatest risk are not being adequately identified and immunised. Implications: Novel immunisation strategies, including contingency management approaches focused on new initiates and adolescents at risk of injecting, should be expanded.

Keywords

• hepatitis B virus
• hepatitis C virus
• injecting drug use
• immunisation
• prospective observational study