Hepatitis B booster dose not necessary for children

Booster dose of Hepatitis B vaccine does not seem necessary to ensure long-term protection in children. Researchers from the University of Milan, Italy conducted a study on previously vaccinated individuals to assess the duration of immunity and the need for the booster dose 10 years after the vaccination. The researching team analysed 1212 children and 446 Italian Air Force recruits vaccinated as infants and adolescents, respectively. They measured the concentrations of antibodies to hepatitis-B surface antigen (anti-HBs) and the presence of antibodies to hepatitis-B core antigen (anti-HBc) at enrolment. Individuals positive for anti-HBc were tested for hepatitis B surface antigen (HBsAg) and hepatitis B viral DNA. Individuals with anti-HBs concentrations at 10 IU/L or more were regarded as protected; whereas those with antibody level less than 10 IU/L were given a booster dose and retested 2 weeks later. Individuals showing post booster anti-HBs concentrations of less than 10 IU/L were offered two additional vaccine doses and retested 1 month after the third dose. After 10 years, protective anti-HBs concentrations (>10 IU/L) were retained in 779 (64%) children and 398 (89%) recruits. Antibody concentrations were higher in recruits than in children. 332 (97%) of 342 children and 46 (96%) of 48 recruits who received a booster showed an anamnestic response, which means renewed rapid production of an antibody on the second (or subsequent) encounter with the same antigen. Pre booster and post booster antibody titres were strongly correlated with each other in both groups. All individuals given two additional vaccine doses showed anti-HBs amounts of more than 10 IU/L 1 month after vaccination. The findings thus suggest that strong immunological memory persists more than 10 years after immunisation of infants and adolescents with a primary course of hepatitis B vaccination.