DIPHTHERIA, TETANUS AND WHOLE-CELL PERTUSSIS-VACCINE COMBINED WITH HEPATITIS-B VACCINES - A COMPARISON OF 2 DOSES (10 MU-G AND 5 MU-G)

Background. A combined diphtheria-tetanus-whole cell pertussis-hepatit is B (DTPwHB) vaccine might facilitate the achievement of universal va ccination of infants against hepatitis B. Methods. A double blind, ran domized, two-armed, single center study was undertaken to evaluate the immunogenicity and reactogenicity of combined tetravalent DTPwHB vacc ine, with two dosages of hepatitis B component(10 mu g and 5 mu g). Th e combined vaccine was tested in the context of a simplified vaccinati on schedule at 1.5, 3.5 and 6 months of age, to 120 healthy infants bo rn to hepatitis B surface antigen-negative mothers after priming with one dose of hepatitis B vaccine (10 mu g) at birth. Antibodies to each antigenic component were measured from blood samples collected immedi ately after birth, pre- and postvaccination blood samples. Results. Th e reactogenicity profiles were similar in the two groups. No serious a dverse events were reported. One month after completion of the four-do se vaccination schedule, all subjects except one in Group 1(10 mu g) h ad protective titers of anti-HBs (10 mIU/ml). At this time the geometr ic mean titer in Group 1 (10 mu g) was higher than that observed in Gr oup 2 (5 mu g), 696 vs. 488 mIU/ml (P = 0.19). One month after three d oses all subjects in both groups had protective antidiphtheria titers and antitetanus titers. The vaccine response rate to the Bordetella pe rtussis component of the vaccine was 88.0% in Group 1 and 96.2% in Gro up 2 (P = 0.86). Conclusion. Both combined tetravalent vaccines are sa fe and immunogenic when administered to infants born to a hepatitis B surface antigen-negative mother, with a 10-mu g dose of priming hepati tis B vaccine at birth. This combined tetravalent DTPwHB vaccine may p lay an important role to promote integration of HE vaccine into the Ex panded Program of Immunization in hepatitis B-endemic areas.