The introduction of a standardised CHO cell-clustering assay for residual pertussis toxin testing is based on the results of two collaborative studies1 run under the auspices of the EDQM’sBiological Standardisation Programme.

The replacement impacts general chapter 2.6.33 Residual pertussis toxin and ten individual monographs on vaccines containing acellular pertussis components. The decision to replace the HIST was approved during the 162nd session of the European Pharmacopoeia (Ph. Eur.) Commission, held in Strasbourg on 20-21 November 2018, and the revised texts will become effective on 1 January 2020.

As part of the same revision exercise, the test for irreversibility of pertussis toxoid has been deleted from monographs on acellular pertussis vaccines. This decision is based on the history of safe use as well as on data confirming that the pertussis toxoid is stable for marketed acellular pertussis vaccines. However, the revised monographs emphasise the need to validate the detoxification process to demonstrate that the toxoid is immunogenic and stably detoxified.