Safety, Immunogenicity, Efficacy, and Effectiveness of Acellular Pertussis Combination Vaccines

Halperin S.A.

1 Dhalousie University, Canada

2 IWK health Centre in Halifax, Nova Scotia, Canada

 

Acellular pertussis vaccines combined with diphtheria and tetanus toxoids were demonstrated to be safe, immunogenic and efficacious in multiple phase 2 and 3 studies during the last decade. Additional combination products that include inactivated poliovirus vaccine, Haemophilus influenzae type b-conjugate vaccine and hepatitis B vaccine have been developed, tested, and licensed for use in children. These broadened combination vaccines have a safety profile which is not substantially different from the original DTaP products. Antibody responses to the component antigens elicited with the expanded combination vaccines are, in general, equivalent to levels achieved when the antigens are administered separately. However, for most (but not all) acellular pertussis combination vaccines, antibody responses to the capsular polysaccharide of Haemophilus influenzae type b are lower with the combination product than when the antigens are given separately. The clinical significance of these lower antibody responses has not been established; several studies have demonstrated both antibody and cellular immune priming, despite the lower antibody levels. In Canada, where acellular pertussis vaccine has been used exclusively since 1998, the virtual elimination of invasive Haemophilus influenzae type b disease has been maintained using the Aventis Pasteur 5-component acellular pertussis vaccine combined with inactivated poliovirus and Haemophilus influenzae b-conjugate vaccine which does not demonstrate any diminished antibody responses. Subsequent to the change from whole-cell to acellular pertussis vaccine, there have been clearly demonstrable decreases in serious vaccine-associated adverse events including febrile seizures and hypotonic-hyporesponsive episodes. Although too early for a definitive conclusion about the effect of acellular pertussis vaccine on the epidemiology of pertussis in Canada, there has been a relative decrease in reported cases in the age cohorts immunized with the new combination vaccine. Acellular pertussis combination vaccines provide a safe, effective, and convenient method of simultaneous immunization against multiple infectious diseases in children.