Seroepidemiology of hepatitis B virus infection in children 12 years after China's expanded program on immunization in Qamdo, Tibet.

Although hepatitis B vaccine (HepB) was first recommended through China's Expanded Program on Immunization (EPI) in 1992, Tibet was able to offer universal HepB vaccination starting only in early 2004. This cross-sectional study was conducted to assess, 12 years after administration of HepB, the seroepidemiology of hepatitis B virus (HBV) infection in children in Qamdo, Tibet. Focusing on a population of individuals ≤ 15 years of age living in Tibet, we analyzed serum samples from 261 healthy children for HBV status based on the presence of hepatitis B surface antigen (HBsAg), antibodies against HBV core antigen (anti-HBc), and antibodies against HBsAg (anti-HBs).