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 hepatitis B vaccine, GenHevac B Pasteur with or without passive immunization with hepatitis B immunoglobulin (HBIG) in high risk neonates born from HBsAg and HBeAg positive mothers was evaluated. Twenty-six neonates (group A) received HBIG 100 IU intramuscularly at birth plus GenHevac B Pasteur 20 micrograms 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 group. It was found that at months 4, 12, 13 and 24 the seroconversion rate in both group A and B were very high in the range of 95-100% with the GMT ranging from 10-160,000 mlU/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 efficacy in neonates group A and B were 95.5% and 89.8% at one year, respectively, with no statistically significant difference. In 46 normal school children (group C) and 48 healthy adults (group D) who received the same dose of GenHevac B Pasteur the seroconversion rates at month 4 after receiving 3 doses of vaccination were 97.8% and 83.3% in group C and group D, respectively. At month 12, the seroconversion rate in group C rose to 100% and was significantly higher than the 89.6% of group D.(ABSTRACT TRUNCATED AT 250 WORDS)

Long term efficacy of hepatitis B immunoprophylaxis in neonates at risk: using different vaccine and schedule.

Passive and active immunization for the prevention of hepatitis B virus (HBV) transmission in neonates born to HBeAg positive carrier mothers was studied using different kinds and dosages of combined hepatitis B immunoglobulin (HBIG) and hepatitis B vaccine. The long term efficacy of these various immunoprophylaxis programmes was evaluated up to 3 years of age. Eight groups of neonates, 20 in each group, received HBIG either the usual dose of 100 IU intramuscularly or intravenously or increased dose to 200 IU, combined with different kinds of hepatitis B vaccine either in full dose or half dose given in different schedules of 0, 1, 2 or 0, 1, 6 months, in some groups also received a booster dose at 12 months. After follow-up for 3 years, there were no statistical significant differences of the results between these 8 different immunoprophylaxis programmes, either in the rate of seroconversion or the protective efficacy as well as the antibody response (anti-HBs titer). The seroconversion rates after 3 years of age in all 8 groups were in the range of 63.6 to 92.9 per cent. The protective efficacy rates at 3 years of age were in the range of 69.7 to 100 per cent.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogenicity and protective efficacy of low dose recombinant DNA hepatitis B vaccine in normal and high-risk neonates.

A low dose of recombinant DNA hepatitis B vaccine (HB-VAX II, MSD) was tested for efficacy in the prevention of perinatal hepatitis B virus (HBV) transmission in normal and high-risk neonates born from HBsAg carrier mothers. A dose of 2.5 micrograms recombinant vaccine was injected intramuscularly at 0, 1, 2 and 12 months of age to 30 newborns from HBsAg negative mother (group I), 30 from HBeAg negative/HBsAg carrier mother (group II) and 30 from HBeAg positive/HBsAg carrier mother (group III). The incidence of persistent HBsAg carrier infants at 13 months of age was 0, 0, and 30.4 percent in groups I, II and III, respectively. The protective efficacy in high risk infants in group III was 65.7 percent. The seroconversion at month 4, after the third dose of vaccination was 96.3, 95.7 and 100 percent in group I, group II and group III, respectively. After a booster dose of vaccination at 12 months of age, the seroconversion rose to 100 percent at month 13 in all three groups. The geometric mean titer (GMT) of anti-HBs antibody at 13 months of age were 2,092, 1,657 and 1,938 mIU/ml in group I, group II and group III, respectively. It is concluded that the low dose (2.5 micrograms) recombinant hepatitis B vaccine using alone is effective in prevention of perinatal HBV transmission in low risk infants (groups I and II), but it is less effective in high risk infants (group III).(ABSTRACT TRUNCATED AT 250 WORDS)