Comparative immunogenicity under field conditions of two recombinant hepatitis B vaccines in 8-10-year-old children

The immunogenicity of two hepatitis B vaccines was compared in 8-10-year-old children immunized in a school program. One year apart, 1129 children received Engerix-B 10 microg vaccine (EB), and 1126 received Recombivax-HB 2.5 microg (RB), following the 0, 1, 6 schedule. Blood samples were collected one month after the third dose. Anti-Hbs were measured by commercial radioimmunoassay. In the EB group, 99.1% of the children seroconverted (>/=2 IU/l) compared to 99.7% in the RHB group (p=0.09). The seroprotection rate (>/=10 IU/l) was similar for both groups: 98.9% in the EB group and 99.2% in the RB group (p=0.66). However, GMCs of anti-HBs were higher in children given EB compared to those given RB (7307 vs. 3800 mIU/ml, p<0.0001). This study showed that both vaccines were highly immunogenic, in the course of a regular field immunization program. However, the difference observed in the antibody levels attained according to the vaccine may play a role in the long-term protection of these children.