Feasibility study to develop a common in vitro D antigen assay for inactivated poliomyelitis vaccines.

A feasibility study was organised to determine the possibilities for development of a common in vitro assay for determination of D-antigen content in inactivated poliomyelitis vaccines (IPV). 3 different methods were tested on a selection of non-combined IPV vaccines from the European market. The results of this preliminary study suggest that for vaccines with a similar strain composition similar results would be achieved regardless of which of the three methods was used. Nevertheless, for one vaccine with a slightly different strain composition the results obtained depended on which method was applied. This highlights the need to take into account the strain composition in any future development of a common method. The study also highlighted the importance of standardising the statistical approach to analysis of results, since one laboratory obtained different sets of results by applying different statistical analysis to the same raw data. While no immediate need was seen for a large collaborative study to establish a common method, participants encouraged the idea of further study, in particular with respect to the different strain compositions. Adaptation of a common method will also require further analysis of the needs for combined vaccines, including the steps and conditions for de-sorption.