Reactogenicity and immunogenicity of a recombinant hepatitis B vaccine compared with a plasma-derived vaccine in young adults.

A study of the immunogenicity and reactogenicity of three doses of lot L (10, 20, 40 micrograms), two doses of lot N (10, 20 micrograms) of the SmithKline Biologicals recombinant DNA yeast-derived hepatitis B vaccine and a 20 micrograms dose of the Merck, Sharp & Dohme plasma-derived hepatitis B vaccine was conducted in young adults under randomized, double-blind conditions. Immunization was carried out according to a 0, 1, and 6 month vaccination schedule. Results indicated that the yeast-derived hepatitis B vaccine was well tolerated and highly immunogenic. Reactogenicity to both yeast- and plasma-derived vaccines was mild in severity and low in incidence with no significant differences appearing between the study groups. One month after the third dose, the yeast-derived vaccines induced a high degree of seroconversion ranging between 97.8% and 100%. The response was not lot- or dose-dependent. The administration of the plasma-derived vaccine resulted in an anti-HBs geometric mean titre approximately twice as high as those elicited by the different yeast-derived hepatitis B vaccine doses one month after the third inoculation. However, 11 months following the third dose of vaccine, the anti-HBs titres were similar in all groups. Revaccination of subjects who no longer had detectable anti-HBs one year after the last vaccine dose resulted in an anamnestic response.