Safety and immunogenicity of a novel mammalian cell-derived recombinant hepatitis B vaccine containing Pre-S1 and Pre-S2 antigens in children.

We tested the safety and immunogenicity of the new recombinant hepatitis B virus (HBV) vaccine produced via expression of the Pre-S1, Pre-S2 and S protein components of the hepatitis B surface antigen (HBsAg). A reduced dose (2.5 micrograms) of the vaccine (Bio-Hep-B) was tested in children aged 4-9 years and was compared to a 10 microgram dose of a licensed vaccine (Engerix-B) in a randomized manner. Both vaccines were administered in 3 doses (0, 1 and 6 month intervals). Adverse events were collected 5 days following each vaccination by a diary card provided to the parents. Immunogenicity was tested by measuring anti-hepatitis B surface antibody (anti-HBs). A total of 217 children were enrolled (162 in the Bio-Hep-B group and 55 in the Engerix-B group). Total adverse events were observed in 35% of the Bio-Hep-B group and 33% of the Engerix-B group, with no differences when each of the potential adverse events was considered. Titers were within the expected range (geometric mean titers post dose 1, 2 and 3 were 45.8, 8360.2 and 1445.7, respectively, for Bio-Hep-B and 36.3, 10316.1 and 1898.7, respectively, for Engerix-B). A trend toward better immunogenicity with Bio-Hep-B was observed at early visits when measured by both seroconversion (anti-HBs > or = 2.1 mIU ml-1) rate and seroprotection (anti-HBs > or = 10 mIU ml-1) rate; however, statistical significance was not reached. We conclude that in children, Bio-Hep-B vaccine at a reduced dose was as safe and as immunogenic as Engerix-B given at the regular pediatric dosage.