Thirty-five years' experience with the whole-cell pertussis vaccine in France: vaccine strains analysis and immunogenicity.

A resurgence in infant and adult pertussis cases has been observed in many countries around 25 years after the introduction of generalised vaccination. An antigenic differences between circulating isolates and vaccinal strains, due to changes in vaccine procedures, could be due to this resurgence. In this study, we analysed the genome and antigenic expression of vaccinal strains of the Aventis Pasteur whole-cell pertussis vaccine from multiple lots stored since 1984. Despite lyophilisation having been performed on these strains for over 30 years, their genome remain conserved, and they still express the major toxins and adhesins. A study in mice confirmed that vaccine lots were highly immunogenic. In conclusion, there is no evidence to suggest that many years of production have resulted in alteration in the French vaccinal strains which quality has remained consistent since its introduction, this can explain its continued efficacy, effectiveness and the lack of epidemics in France.