Persistence of protection of hepatitis B vaccine and response to booster immunization in 2- to 12-year-old children

Neonatal vaccination against hepatitis B virus (HBV) infection was launched in 1998 in Turkey. The aim was to evaluate the persistence of seroprotection after HBV vaccination in order to determine the necessity of a single booster dose in 2- to 12-year-old children. This study was conducted retrospectively using hospital records of the children aged 2-12 years old who attended the pediatric outpatient clinics of Diskapi Training and Research Hospital, Ankara, Turkey between January 2010 and June 2011. Children who had received three doses of HBV vaccination in their infancy were included. A total of 530 children enrolled into the study, and 352 (66.4 %) of them had protective antibody to hepatitis surface antigens (anti-HBs) titer greater than 10 mIU/ml. The proportions of children with low, intermediate, and high anti-HB titers are different for those under 3 years of age. The majority were in the intermediate category. Those aged 4-10 years and 11 or older represented two-thirds of the children with high titers (p = 0.000). None of the children had chronic HBV infection. Unprotected children responded well after receiving the booster dose. The mean anti-HB concentration after the booster dose was more than 200 times higher than the mean antibody concentration before (p < 0.001). Conclusion: Our data suggest that HBV vaccination may confer long-term immunity. Use of routine booster doses of vaccine at these ages does not appear necessary to maintain long-term protection in successfully vaccinated immunocompetent children in the region.