ACELLULAR PERTUSSIS VACCINES IN INFANTS - EVALUATION OF SINGLE-COMPONENT AND 2-COMPONENT PRODUCTS

Two acellular pertussis vaccines, one containing only LPF toxoid (25 m u g) and the other containing LPF toroid (25 mu g) and FHA (25 mu g) a nd each combined with diphtheria and tetanus toxoids, were evaluated i n two groups of 25 infants. A third group of 25 infants served as cont rols and received a DTP whole-cell pertussis vaccine. Infants given ei ther acellular pertussis vaccine had significant fewer local and syste mic reactions than infants given whole-cell vaccine. Among the three v accine groups, infants given the LPF vaccine (single component) had th e highest concentration of antibody to LPF after three immunizations. Infants receiving the LPF/FHA vaccine (two-component) had the highest concentration of antibody to FHA after three immunizations. Infants va ccinated with the two-component vaccine had a significantly lower sero logical response to LPF than infants given the single component vaccin e, as measured by either enzyme-linked immunosorbent assay or CHO cell assay. Further studies are necessary to determine why differences in immunogenicity of the two investigational vaccines occurred.