IMMUNOGENICITY AND EFFICACY OF A RECOMBINANT-DNA HEPATITIS-B VACCINE,GENHEVAC-B PASTEUR IN HIGH-RISK NEONATES, SCHOOL-CHILDREN AND HEALTHY-ADULTS

The immunogenicity and the protective efficacy of a recombinant DNA he patitis B vaccine, GenHevac B Pasteur with or without passive immuniza tion with hepatitis B immunoglobulin (HBIG) in high risk neonates born from HBsAg and HBeAg positive mothers was evaluated. Twenty-six neona tes (group A) received HBIG 100 IU intramuscularly at birth plus GenHe vac B Pasteur 20 mug at birth, 1, 2 and 12 months of age while another 23 neonates (group B) received only GenHevac B Pasteur vaccine. Forty high risk newborns who received no immunization served as control gro up. It was found that at months 4, 12, 13 and 24 the seroconversion ra te in both group A and B were very high in the range of 95-100% with t he GMT ranging from 10-160,000 mIU/ml. In the control group of infants , 85% had HBsAg positive at one year of age but it was only 3.8% and 8 .7% in vaccinated groups A and B, respectively. The protective efficac y in neonates group A and B were 95.5% and 89.8% at one year, respecti vely, with no statistically significant difference. In 46 normal schoo l children (group C) and 48 healthy adults (group D) who received the same dose of GenHevac B Pasteur the seroconversion rates at month 4 af ter receiving 3 doses of vaccination were 97.8% and 83.3% in group C a nd group D, respectively. At month 12, the seroconversion rate in grou p C rose to 100% and was significantly higher than the 89.6% of group D. However, at month 13, after a booster dose at month 12, the serocon version rate of group D also rose to 95.8%, close to the 100% of group C. The GMT of anti-HBs responses in school children were statisticall y significant higher than those of healthy adults at months 4, 6 and 1 2, but both groups showed similar anamnestic antibody responses after the booster dose at month 12 with a GMT of 27,800 mIU/ml and 12,520 mI U/ml in groups C and D, respectively. This full dose of GenHevac B Pas teur produces high immunogenicity and protective efficacy in high risk neonates as well as in school children and healthy adults. During the first year the seroconversion rate in healthy adults was lower than t hat of school children but finally catched up at month 13 with high GM T levels. It is concluded that full dose recombinant DNA hepatitis B v accine alone is equally effective as the vaccine plus HBIG in preventi on of vertical HBV transmission from HBeAg carrier mothers to their hi gh risk neonates.