The prevalence of hepatitis B core antibody in vaccinated Chinese children: A hospital-based study

•This is the first serosurvey of anti-HBc in immunized Chinese children.•The were similar 3 stages in hepatitis serological markers.•HBV breakthrough infection occurred in vaccinated children >9-year-old. After nearly 30 years of immunization, there is little known about the prevalence of hepatitis B core antibody (anti-HBc) in Chinese children. The clinical significance of anti-HBc would be more and more important. In this study, we had tried to analyse the prevalence of anti-HBc in vaccinated Chinese children, exploring the post-immunization status based on a large sample sized investigation. Proportions of anti-HBc were analysed among 215,627 hospitalized Chinese children immunized with HBV vaccination in this study. The proportions of anti-HBc were divided into 3 stages: 36.6% in 0-year-old group, followed by 1- to 10-year-old which stayed relatively stable (5.69 ± 0.40%, [4.86–6.28%]), and significant increasing within 11- to 16-year-old (7.80 ± 1.24%, [6.62–9.74%]), meanwhile, similar changes of HBsAg were showed in the corresponding ages, and significantly increased in children older than 9-year (1.40%, [1.00–2.04%]), comparing with 0.30% in 0-year-old, 0.55 ± 0.13% (0.30–0.64%) in 1- to 9-year-old. The average level of anti-HBc maintains 5.99% in children aged 1- to 16-year with 0.63% for HBsAg. This is the first study of the prevalence of anti-HBc in vaccinated Chinese children: 36.6% of anti-HBc-positivity was found in 0-year-old group, which could be maternal in origin. Relatively high prevalence of anti-HBc may not be ignored in children aged 1- to 16-year-old. Strangely, our data also showed that HBV breakthrough infection would occur in immunized Chinese children older than 9-year-old, and more attention is needed on those children.