DOSE-RESPONSE TO A 2-COMPONENT ACELLULAR PERTUSSIS-VACCINE IN INFANTSAND COMPARISON WITH WHOLE-CELL VACCINE

in an effort to determine the optimal dose of pertussis toroid (PT) an d filamentous haemagglutinin (FHA) for use in a cellular pertussis vac cines we compared the immunogenicity and safety of acellular pertussis vaccine combined with diphtheria and tetanus toxoids containing 12.5 mu g (DTaP-12.5) or 25 mu g (DTaP-25) each of PT and FHA with a whole- cell pertussis vaccine in infants immunized at 2, 4 and 6 months of ag e. Recipients of acellular vaccines developed higher anti-FHA concentr ations and more rapid anti-PT serological responses than infants who r eceived whole-cell pertussis vaccine combined with diphtheria and teta nus toxoids (DTP). A dose response was noted; infants immunized with D TaP-25 developed significantly (P < 0.03) higher anti-FHA and anti-PT levels than infants who received DTaP-12.5. No rise in agglutinin titr es was noted for recipients of the acellular vaccines although this va ccine stimulated increases in agglutinins when given as the fourth or fifth dose to children who had received three doses of DTP. The rates of erythema, induration, pain, irritability, crying, increased sleepin ess,and decreased appetite were significantly (P less than or equal to 0.05) lower in infants who received a cellular vaccines than in infan ts who received DTP. When the data from injections at 2, 4 and 6 month s of age were combined, no significant differences in the rates of any adverse event were noted for recipients of DTaP-12.5 Sor DTaP-25. The rates of most adverse reactions following DTP decreased from the firs t to the third immunization except fever, which increased. For a cellu lar vaccine recipients, the rates of fever and erythema increased some what from the first to the third injection but remained far below the rates following DTP. The acellular vaccine was safe and immunogenic, a nd a dose-response effect was demonstrated. (C) 1998 The International Association of Biological Standardization.