Hepatitis B virus infection and vaccination among people who use drugs in Xi'an, China

Background: While hepatitis B virus (HBV) infection in children has declined dramatically in China due to the vaccination strategy for newborns, HBV infection in high-risk adults is receiving an increasing attention. The number of people who use drugs (PWUD) in China is huge, but their status of HBV infection and vaccination is less reported, especially from large samples. The related knowledge can help decision makers develop the further strategy of HBV prevention and control. Methods: A seroepidemiological survey was conducted in all four compulsory isolated detoxification centers (CIDCs) and all eight methadone maintenance treatment (MMT) clinics located in Xi'an, China. All PWUD who were undergoing detoxification or treatment in these settings were included. A questionnaire was designed to obtain the information of HBV vaccination history of participants, and sociodemographic and behavioral data of participants were obtained from the registration records of their respective CIDCs or MMT clinics. Results: A total of 4705 PWUD participated in the survey. Positive rates of HBsAg (current infection) and HBsAg or anti-HBc (current/past infection) were 5.50% and 58.02%, notably higher than those reported for the general adult population in the same province during the same period. As age increased, the anti-HBc positive rate increased with statistically significant trend. The all-negative for HBsAg, anti-HBc, and anti-HBs accounted for 28.82%. Only 18.49% were identified by the questionnaire as having received HBV vaccine. The logistic regression found that compared with identified vaccinated PWUD, those unsure if having been vaccinated and those identified non-vaccinated had a significantly higher HBV current/past infection rate, with an increasing trend. Conclusion: PWUD are a high-risk adult group of HBV infection in China. Of them, more than half have not received HBV vaccine, and a significant portion are susceptible to HBV. Catch-up vaccination is need for this population to prevent and control HBV transmission.