Rational arguments for regulatory acceptance of consistency testing: benefits of non-animal testing over in vivo release testing of vaccines.

For several vaccines, in vivo release assays have been replaced leading to an optimized control strategy. For other vaccines, new assays are being developed, that can expected to be introduced within 5-10 years. From a scientific, logistical and animal welfare perspective, it would be beneficial to substitute all existing in vivo batch release assays for vaccines. Given the challenges relating to development, validation and acceptance of new methods, and considering the relatively low prices of some legacy vaccines, this cannot be done without government incentives and supportive regulatory authorities from all regions.