Immunogenicity of a two-component (PT & FHA) acellular pertussis vaccine in various combinations.

Immunogenicity data for the pertussis components of the French diphtheria-tetanus-two component acellular pertussis vaccine (DTaP(2Fr)) obtained after primary series of immunizations were compiled from 75 study groups comprising 36 clinical trials or vaccination programs conducted between 1987 and 2006. DTaP(2Fr) vaccine was administered either as a standalone vaccine or as the backbone of several combination vaccines that included IPV, HepB and/or PRP-T antigens. Most of the variability in responses was associated with differences in the schedules, and to a lesser extent the geographical region where the study was performed, suggesting the importance of ethno-ecological factors. However the addition of other vaccine antigens did not affect the immunogenicity of the aP(2Fr) antigens. The immune responses to the PT and FHA antigens of the DTaP(2Fr) vaccine used in the Sénégal efficacy trial, which established its good efficacy relative to a highly effective DTwP vaccine, was in the middle of the range of titers observed during other studies using the 2-4-6 months schedule conducted with the same vaccine. The consistent immunogenicity of the DTaP(2Fr) vaccine is accompanied by effectiveness in controlling pertussis disease in the areas where it is used on a large scale with good vaccination coverage.