Whooping cough or Pertussis is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis. The introduction of pertussis-containing vaccines into the immunization schedule of infants and children has reduced pertussis incidence worldwide, although sporadic outbreaks, even with mortality, remain relatively common in case of poor vaccination coverage. The whole-cell Pertussis (wP) vaccine was developed more than a century ago, and it is still largely used in developing countries because of its proven efficacy and long-lasting immunity, although the vaccine also induces more frequent side-effects than the acellular Pertussis vaccine.
According to existing regulatory requirements, every batch of vaccine needs to be tested for its safety and potency before entering the market. The potency test for wP vaccine is the Mice Protection Test (MPT) or Kendrick test (KT) which is based on the immunization and intracerebral challenge of mice with a lethal dose of Bordetella pertussis bacteria. Although, the MPT has been used for a long time, its use has been disputed for various reasons.
For those reasons, the need for a better potency test is widely recognized and attempts have been made to develop more acceptable alternatives. One of the developed alternative assays is the Pertussis Serological Potency Test (PSPT).
An international collaborative study was organized and run under the aegis of the Biological Standardisation Programme (BSP) with the intent of bringing together vaccine quality control laboratories both from the private (manufacturers) and the public (OMCLs) sectors (BSP-104 Project). The aim of the BSP-104 was the evaluation of the transferability and robustness of the guinea pig PSPT selected in the 2008 study and also including the mouse PSPT. It was recommended to confirm this finding in an additional in-house validation study, but since the wP vaccine is no longer used in the immunization programmes in Europe, no agreement was reached in continuing the study.
The aim of the current study is to follow up on the BSP study in order to allow in-house validation of the PSPT in laboratories still manufacturing wP vaccines, and setting the basis for its implementation as routine testing approach.
How the project will uniquely contribute to solving the problem
1. The unique approach of the in-house validation of the PSPT would provide the vaccine manufacturers and NCLs from the developing countries with the opportunity to validate the method PSPT protocol for their own specific wP containing vaccines (e.g. DTP, DTPHepB, DTPHib, Pentavalent, Hexavalent), using the regional standards and regional reference vaccines, following their own production and testing procedures. That will allow manufacturers to gain hands-on confidence on the method and gather key validation data to present to regulatory authorities and initiate a dialogue that could lead to the acceptance of the PSPT for their specific products.
2. National Control Laboratories (NCLs) have been invited to participate as well, allowing them to perform a similar in-house validation experience that could be shared within the members of WHO National Control Laboratories Network for Biologicals (WHO-NNB) [21] and facilitate the pathway for regulatory dialogue and recognition by consensus.
•Production of about 2000 vials of assay specific (ELISA) coating antigen material.
•Physico-chemical Characterization of the produced coating antigen material
•Shipment of the coating antigen material to all 10 participating laboratories
•Data collection, analysis, and assay optimization spreadsheets
15 Workshops and a Final hybrid Meeting
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Developing Countries Vaccine Manufacturers Network