Two hundred healthy adults seronegative for HBV markers received three 10 or 20 mcg
injections of a
vaccine formulated from
HBsAg produced by a recombinant strain of the yeast Saccharomyces cerevisiae. The
vaccine was administered intramuscularly at 0, 1, and 6 months in the deltoid region. The seroconversion rates, expressed in GMT/IU/1 were determined at 1, 2, 6, 7, 12, 24, 36 and 48 months following the initial injection. No severe or serious adverse reactions attributable to the HB
vaccines were observed in any subject. The seroconversion rates following the 20 mcg dose of
recombinant vaccine were always higher than those observed after the 10 mcg dose, but the differences were not statistically significant. Also the GMT values were lower after the 10 mcg dose of
vaccine. Females showed a higher anti-HBs response than males; an age-dependent effect was observed in the anti-HBs response as regards both the percentage of responders and the antibody concentrations in the serum. No adverse reactions to the
vaccine were observed. The
rDNA vaccine did not induce a response to yeast-derived impurities and did not increase anti-yeast
IgE antibody titres. The results of this study have shown that the Amgen
rDNA vaccine is safe and clinically well tolerated, and that it provides protection against
infection and disease. A vaccination dose of 20 mcg appears more advantageous for healthy adult subjects.