CONTROL OF HEPATITIS-B - EVALUATION OF 2 DIFFERENT VACCINAL SCHEDULESIN NEWBORNS FROM HBSAG NEGATIVE MOTHERS

504 healthy infants, born to HBsAg negative mothers from May 1st to De cember 31st 1991, were randomly allocated to an accelerated (group A) or traditional (group B) immunization schedule. The group A infants we re immunized at 4 days, 1 month and 3 months of life with 10 mug of re combinant HBV vaccine (Engerix B(R), SKF) while the group B infants we re immunized at 4 days, 1 month and 6 months of life with the same dos e of vaccine. One month after the first dose of vaccine, 9.2% of the i nfants in both groups had an HBsAb serum level >10 mIU/ml. One month a fter the booster dose, at 4 months of life for group A and at 7 months for group B, 97.40% and 98.53% of the infants presented a serum level >10 mIU/ml respectively. None in group A and only 2 patients in group B could be considered non-responders (serum concentration below 2 mIU /ml) and 4 infants in group A and 4 in group B were considered hypo-re sponders (serum level between 2.1 and 9.9 mIU/ml). Immunogenetic study performed on the 2 non-responders and 6 of the hypo-responders, revea led the presence in all but two of the HLA haplotypes, classically inv olved in the lack of hyporesponsiveness to foreign peptides, namely: H LA-DR7; DQ2, DR4; DQ3, DR15, DQ6 and DR3; DQ2. Surprisingly, 2 hypo-re sponders carried the HLA haplotypes (DR11, DQ7 and DR13, DQ6), usually associated with hyperresponsiveness. Both vaccinal cycles provided ev idence that infants respond well to vaccination, started at birth, aga inst hepatitits B virus with a high degree of protection. The percenta ge of infants with antibody levels >100 mIU/ml was higher in group B ( 87%) than in group A (59%). It is therefore advisable to use an accele rated vaccinal cycle only in infants at very high risk of HBV infectio n, and the traditional vaccinal cycle in low risk situations, because of the better response with higher serum concentrations of anti-HBsAg antibodies.