Immunogenicity of plasma-derived hepatitis B vaccine in preterm infants

The objective was to determine whether plasma-derived hepatitis B vaccine is immunogenic in preterm appropriate for gestation babies when administered at birth and to compare the immunogenicity between 5 micrograms and 10 micrograms doses of the vaccine in these babies. Fifty preterm neonates (31-36 weeks gestation) were randomized to receive 5 micrograms or 10 micrograms doses of plasma-derived hepatitis B vaccine at birth, with subsequent doses 1 and 6 months later. Serum specimens were obtained a month after each dose of the vaccine and were tested for antibody to hepatitis B surface antigen (anti-HBs). Thirty six babies (gestation 31-36 weeks), 18 from each group competed the study. While 89.2% of the babies seroconverted, 82.1% achieved seroprotective titres of anti-HBS (> 10 mIU/ml). There was no difference between weight, gestational age, age of administration of vaccine and age of estimation of anti-HBs between 5 micrograms and 10 micrograms groups. The difference in the seroprotective rates were not statistically different between the groups (5 micrograms 78.5%; 10 micrograms--85.7%). Although immune response to plasma derived hepatitis B vaccine in preterm babies is suboptimal when the first dose is administered at birth, the full course achieves adequate seroprotective levels.