Acellular pertussis vaccine: immunogenicity and safety of an acellular pertussis vs. a whole cell pertussis vaccine combined with diphtheria and tetanus toxoids as a booster in 18- to 24-month old children.

An acellular pertussis vaccine principally containing two purified pertussis antigens, filamentous hemagglutinin and lymphocytosis-promoting factor, combined with diphtheria and tetanus toxoids was compared to conventional diphtheria-tetanus toxoids-whole cell pertussis for adverse effects and serologic responses in a group of 120 children who were from 18 to 24 months of age. Three vaccinations at 2, 4 and 6 months of age with diphtheria-tetanus toxoids-whole cell pertussis had been administered previously. Adverse effects occurred more frequently with the diphtheria-tetanus toxoids-whole cell pertussis than with diphtheria-tetanus toxoids-acellular pertussis vaccine. Fever occurred significantly more often and to a higher degree in the whole cell pertussis vaccine recipients with a peak difference occurring 6 hours after immunization (P = 0.00008). Local swelling, redness, warmth and tenderness at the injection site also occurred significantly more frequently following whole cell pertussis vaccination. No major sequelae were noted in either group. The antibody responses to lymphocytosis-promoting factor were similar for the two vaccines. The diphtheria-tetanus toxoids-acellular pertussis vaccine produced significantly lower pertussis agglutinin titers (P = 0.00001) but significantly higher antibody to filamentous hemagglutinin (P = 0.05) and to diphtheria (P = 0.03). The protective role of antibody to pertussis agglutinins vs. filamentous hemagglutinin and lymphocytosis-promoting factor continues as a central issue in the quest for a new pertussis vaccine. A clinical efficacy trial is needed.