Reactogenicity and immunogenicity of a new recombinant hepatitis B vaccine containing Pre S antigens: A preliminary report

A new vaccine against hepatitis B virus (HBV) infection, produced in mammalian Chinese hamster ovary (CHO) cells, contains the small (s), middle (Pre S2) and large (Pre S1) surface proteins of HBV. Three injections of a 5-μg or 10-μg dose were administered intramuscularly (i.m.) at 0, 1 and 6 months to a group of 105 young adults, who were monitored for a period of 6 months after the third injection. Seroconversion rates were 100% after the second injection of the 5-μg or 10-μg dose. Geometric mean titres of HBsAb at 1 month after the third injection were 12 156 mIU ml^-1 and 13 482 mIU ml^-1 in those receiving the 5-μg and 10-μg dose respectively. The vaccine was well tolerated with no significant adverse events. These preliminary results suggest that the Pre S-s recombinant vaccine, produced in mammalian cells, is highly immunogenic, leading to 100% seroconversion in the population tested after injection of only two doses of 5 μg.