Validation of alternative potency assays for influenza vaccines requires clinical studies

Readers of this Special Issue of Vaccine are likely unified by a desire to enhance vaccine efficacy and improve vaccine manufacturing efficiency. For influenza vaccines, challenges to achieving those goals are many, and range from improved surveillance to less cumbersome production platforms and more reliable performance verification. Specifically, demand is growing for an alternative vaccine potency assay. Assuming that a replacement potency assay is found to be promising, one question will be: how will it be judged to be accurate? It is generally agreed that any potential replacement for SRID will have to exhibit good correlation with SRID and yield a value within ± 20% of the SRID determined potency. In my opinion, SRID itself has enough limitations that judging alternatives relative to that particular standard will not ensure that the industry as a whole transitions to an improved method. In fact, it could blind us to an assay that may ultimately provide a better predictive measure of vaccine efficacy (or immunogenicity). There is only one way to verify that measured potency is correlated with, and predictive of, measured immunogenicity - test the relationship in clinical studies.