| Abstract: | OBJECTIVE--To compare the immunogenicity and reactogenicity of a two-component acellular pertussis vaccine with a whole-cell diphtheria and tetanus toxoids and pertussis vaccine (W-DTP) when administered as a booster to children 4 through 6 years of age. DESIGN--This was a randomized, double-blind study. SETTING--Children in this study were from three general pediatric practices (two were private, one was university-affiliated). PARTICIPANTS--Three hundred and sixteen 4- through 6-year-old children who had received four previous W-DTP immunizations at the recommended times were studied. SELECTION PROCEDURES AND INTERVENTIONS--Children were randomly assigned in a 1:3 ratio to receive either W-DTP or one of three lots of acellular diphtheria and tetanus toxoids and pertussis vaccine (A-DTP). The A-DTPs contained 3.75 micrograms each of lymphocytosis promoting factor and filamentous hemagglutinin protein nitrogen per 0.5 mL and the same concentrations of diphtheria and tetanus toxoids as W-DTP. Serum samples were obtained on the day of immunization and 4 to 6 weeks later. Adverse reactions were recorded by parents at 6, 24, 48, and 72 hours. MEASUREMENTS AND RESULTS--An indirect enzyme-linked immunosorbent assay (ELISA) method determined IgG antibody response to lymphocytosis promoting factor, filamentous hemagglutinin, and tetanus toxoid; a CHO cell assay measured neutralizing antibodies to pertussis toxin; and serum neutralization on VERO cells assayed diphtheria antitoxin. One month after booster doses were administered, the geometric mean antibody levels for A-DTP vs W-DTP were IgG filamentous hemagglutinin, 362 vs 104 ELISA U/mL; IgG lymphocytosis promoting factor, 408 vs 81 ELISA U/mL; CHO cell, 210 vs 107; diphtheria, 21.7 vs 12.1 U/mL; and tetanus, 2.86 vs 2.04 Eq/mL. Following immunization with A-DTP, local and systemic adverse experiences were 30% to 50% and 20% to 30% fewer, respectively, as compared with W-DTP. CONCLUSIONS--The BIKEN A-DTP vaccine used in this study demonstrates enhanced immunogenicity to lymphocytosis promoting factor, filamentous hemagglutinin, and other measured antigens and less reactogenicity compared with licensed W-DTP corrected]. |
