IMMUNOGENICITY OF 2 DIFFERENT DOSAGES (10-MU-G AND 5-MU-G) OF RECOMBINANT-DNA HEPATITIS-B VACCINE IN HEALTHY NEONATES

The immunogenicity of a half (5 mu g) and a full (10 mu g) dosage of r ecombinant DNA yeast-derived hepatitis B vaccine (HB-Vax-DNA) in healt hy neonates was assessed in order to compare two candidate dosages of vaccine. After randomization 174 newborns of HBsAg-negative mothers en tered the study. Neonates received four doses of either 10 or 5 mu g h epatitis B vaccine, according to the DTP-polio immunization schedule a t months 3, 4, 5 and 11. No serious adverse reactions were observed; 1 5.5% of vaccinated newborns suffered mild transient local symptoms. Th e vaccine was highly immunogenic il respective of dosage of vaccine; a ll infants developed anti-HBs levels greater than or equal to 10 IU l( -1), 99% greater than or equal to 100 IU l(-1). A dosage of to mu g he patitis B vaccine produced higher antibody levels than 5 mu g hepatiti s B vaccine after primary vaccination (first three doses) but not afte r booster vaccination (fourth dose) (p = 0.06 and 0.75, respectively). Either vaccine dosage can be recommended for incorporation in the Exp anded Programme on Immunization in the Netherlands.