Objective To explore the long-term protective efficacy of neonatal immunoprophylaxis in children whose mothers have hepatitis B virus (HBV).

Methods A cohort of 246 children whose mothers have hepatitis B and hepatitis B surface antigen (HBsAg) negative from November 2011 and March 2012. They were scheduled to have a second follow-up from January to May 2017. The data of hepatitis B revaccination and hepatitis history during two follow-ups were recorded, and blood samples were collected for the hepatitis B markers examination.

Results A total of 197 (80.1%) children, with a mean age of (8.9±1.4) years, participated in the follow-up. All children were HBsAg negative, and 99 (50.3%) children were anti-HBs positive (≥ 10 mU/mL). during the two follow-ups, 31 children were revaccinated with the hepatitis B vaccine. Among these children, the median anti-HBs level increased from 10.7 to 98.4 mU/mL (P < 0.05), and the anti-HBs positive rate increased from 51.6% to 93.5% (P < 0.05). Among 166 children who did not receive revaccination, the median anti-HBs level dropped from 41.7 to 7.3 mU/mL (P < 0.05), anti-HBs became negative in 67 children, and the positive rate of anti-HBs decreased from 77.7% to 42.2% (P < 0.05). Of 37 children, with anti-HBs < 10 mU/mL at the first follow-up, 28 (75.7%) still had anti-HBs < 10 mU/mL. In addition, 30 (18.1%) of the 166 un-revaccinated children showed increased anti-HBs levels, but no one was anti-HBc positive.

Conclusions After neonatal immunoprophylaxis, anti-HBs level in children of HBsAg-positive mothers was declined with the growing age and most unrevaccinated children had anti-HBs < 10 mU/mL, but none of them was infected with HBV. These results indicate that neonatal immunoprophylaxis has long-term protection against HBV and revaccination is not required.