A serological and molecular survey of hepatitis B in children 15 years after inception of the national hepatitis B vaccination program in eastern China

The emergence of mutations in the hepatitis B virus (HBV) S gene has threatened the long‐term success of vaccination programs since the worldwide introduction of effective vaccines against hepatitis B. This study was conducted on 5,407 children (0–8 years old) in eastern China in 2007. We analyzed the prevalence of HBsAg, anti‐HBs, and “a”‐determinant mutations in the HBV S gene by microparticle enzyme immunoassays, PCR, and DNASTAR software. The total HBsAg prevalence was 1.52% (82/5,407) in the children and increased with age. In contrast, the positive rate (65.42%, 2,374/3,629) and the titers of anti‐HBs decreased with age. The predominant infection was HBV of genotype C and serotype adr (45/51; 88% of cases). Mutations of I126T, amino acid 137 (nt553T deletion mutation), G145A, G145R, and F158S were found in the children; the mutations of amino acid 137 and F158S have not been reported previously. The total prevalence of mutant strains was 14% (7/51). To investigate whether the infection resulted from maternal transmission, we compared the S gene sequences in 16 mother–child pairs. Fourteen mother–child pairs exhibited the same HBV genotype, with 99.5–100% sequence homology in the S gene, while two pairs exhibited different genotypes. This study suggested that the hepatitis B vaccination strategies in eastern China have been successful. Although the emergence of “a”‐determinant mutations in the HBV S gene have resulted in HBV infection in immunized children, this does not pose a threat to the vaccination strategies. The HBV‐infected children had contracted the infection via vertical transmission. J. Med. Virol. 81:1517–1524, 2009. © 2009 Wiley‐Liss, Inc.