[Immunogenicity and harmlessness in the newborn of a vaccine (GenHevac B) containing the antigens S and pre-S2].

A study to evaluate the safety and immunogenicity of a recombinant hepatitis B vaccine containing the S and pre-S2 antigens (GenHevac B Pasteur) was conducted in healthy newborn infants. All infants received 20 micrograms of vaccine within 24 hours after birth, at 1 and 2 months with a booster injection at month 12. The vaccine was administered alone in 19 infants born to low risk mothers, i.e. surface antigen (HBsAg)-negative and antibody to the core antigen (Anti-HBc)-positive mothers. The vaccine was administered in combination with 100 IU hepatitis B immune globulin (HBIg) at birth and one month in 18 infants born to high risk mothers, i.e. HBsAg positive mothers. In the group not receiving HBIg, the anti-HBs seroconversion rate at the 10 mlU/ml threshold was 50% one month after the first injection. In both groups, the anti-HBs seroconversion rates were 100% one month after the third injection and above 85% one month after the second injection. After booster injection, more than 90% of the infants had an anti-HBs titre above 1,000 mlU/ml that will probably provide them with adequate protection for several years. The kinetics of the anti-pre-S2 response was similar to those of the anti-HBs response and 100% infants in both groups had seroconverted one month after the second injection of the vaccine. The side effects were scarce, all mild and transient. Given the protective role of the anti-pre-S2 antibodies, the precocity of the response to pre-S2 antigen may therefore increase the effectiveness of hepatitis vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)