Comparison of a fifth dose of a five-component acellular or a whole cell pertussis vaccine in children four to six years of age

Background and objectives. Acellular pertussis vaccines are now preferred f or all five childhood immunization doses; however, there are few data on th e safety and immunogenicity of five consecutive doses. This study compared a fifth dose of an acellular and a whole cell pertussis vaccine in 4- to 6- year old children previously immunized with four doses of acellular or whol e cell pertussis vaccine. Study design. In a double blind, multicenter study, 366 healthy children we re randomly allocated to receive a single injection of a 5-component acellu lar or a whole cell pertussis vaccine, each combined with diphtheria and te tanus toxoids and inactivated poliovirus vaccine. Results, Although injection site redness greater than or equal to 50 mm and swelling greater than or equal to 50 mm were common in children who had re ceived five doses of acellular (50% and 48.1%, respectively) or whole cell (66.2% and 59.7%) pertussis vaccine, limb soreness and limitation of motion were less frequently reported after acellular (1.9% and 0%) than after who le cell (49.2) and 36.3%; P < 0.0001) pertussis vaccine. Pre-fifth dose ant ipertussis antibody titers were higher in children who previously had recei ved four doses of acellular pertussis vaccine. Postimmunization antibody ti ters against pertussis toxin, filamentous hemagglutinin, pertactin and teta nus toxin were higher in recipients of five doses of acellular pertussis va ccine, whereas antibody titers to diphtheria toxin, pertussis fimbriae and poliovirus serotypes were higher in recipients of five doses of the whole c ell pertussis vaccine (P < 0.05 for all comparisons). Conclusions. A regimen consisting of five doses of a five component acellul ar pertussis combination vaccine is safe and immunogenic in preschool child ren. Local adverse reactions are common but are less painful and activity-l imiting than a regimen of five doses of a whole cell pertussis vaccine.