Comparison of results for phase I studies with recombinant and plasma-derived hepatitis B vaccines, and controlled study comparing intramuscular and subcutaneous injections of recombinant hepatitis B vaccine.

A comparison was made of the results obtained in separate Phase I studies conducted in Japan on a recombinant hepatitis B vaccine (HBX-R) and a plasma-derived hepatitis B vaccine (H-B-VAX). Recombinant hepatitis B vaccine was administered intramuscularly (IM) to 40 subjects in a dose of 10 micrograms, while H-B-VAX was administered IM to 35 subjects in a dose of 20 micrograms. Each subject received three doses of the vaccine at times zero, 1 month and 6 months. In both trials, at the end of 7 months from the first vaccination all vaccinees had become seropositive for anti-HBs antibody. During the 1-6 month period after the first dose, the seroconversion rate was always higher in the H-B-VAX subjects than in the HBX-R subjects. The anti-HBs antibody titre was also always higher in the H-B-VAX group during that same 6-month period, but there was no longer any difference at the 7th month (H-B-VAX: HBX-R = 1064: 1164 IU/L). In an additional study on the effect of the administration route on the efficacy of HBX-R, 124 subjects were randomly allotted to an IM group and a subcutaneous (sc) group. In each group, HBX-R was administered in 3 doses of 10 micrograms, again at time zero, 1 month and 6 months. At the end of the 7th month, the anti-HBs seroconversion rates were 98% (55/56) in the IM group and 97% (57/59) in the sc group.(ABSTRACT TRUNCATED AT 250 WORDS)