A collaborative assay of the proposed third British Reference Preparation for Pertussis Vaccine and of the relative potencies of the second International Standard and the second British Reference Preparation for Pertussis Vaccine.

A collaborative assay has been carried out to estimate the mouse protective potency of a freeze-dried preparation of Bordetella pertussis (88/522) intended to serve as the third British Reference Preparation for Pertussis Vaccine (third BRP). The opportunity was also taken of reassessing the relationship between the second International Standard for Pertussis Vaccine and the second British Reference Preparation for Pertussis Vaccine (second BRP). Workers in nine laboratories took part in the study and together completed 19 assays which were considered to be statistically valid. Based on the results of the study it is proposed that ampouled preparation code number 88/522 be established as the third BRP with an assigned potency of 50 IU per ampoule. The evidence of this study also suggests that the relationship between the second International Standard for Pertussis Vaccine and the second BRP has not changed significantly since they were originally established.