COMPARATIVE-STUDY OF THE IMMUNOGENICITY AND SAFETY OF 2 DOSING SCHEDULES OF HEPATITIS-B VACCINE IN NEONATES

Healthy Egyptian neonates born to hepatitis B surface antigen (HBsAg)- seronegative mothers were randomly enrolled in one of three vaccinatio n schedules. A dose of 2.5 mu g of recombinant HE vaccine was given at birth, two, and six months of age (group A) or two, four, and nine mo nths of age (group B). These two groups and a third control group (gro up C) also were given the other routine childhood vaccines (BCG, DPT, polio, and measles). Blood samples were taken one month after the thir d vaccine dose in groups A (seven months of age) and B (10 months of a ge), and a second follow-up blood sample was taken at the age of 18 mo nths for all three groups. Sera were tested for HBsAg and antibody to hepatitis B core antigen, and quantitatively for antibody to hepatitis B surface antigen (anti-HBs) using commercial enzyme immunoassay kits . The vaccine was well tolerated and side effects were limited to loca l soreness, redness, or temporary swelling. Among 590 infants who were followed-up, good (51-300 mIU anti-HBs/ml) or excellent (> 300 mIU/ml ) immune responses occurred in 85% of the infants in group A and in 96 % in group B. Geometric mean titers of anti-HBs at the first and secon d follow-up were 306 and 55 mIU/ml in group A, and 1,492 and 147 mIU/m l in group B. The recombinant HE vaccine is safe and immunogenic when given in three doses of 2.5 mu g in either regimen, but delay of the b ooster dose of the vaccine until nine months after birth produced a hi gher immune response.