Maintenance of vaccine stability through annual stability and comparability studies

Evaluation of vaccine stability does not end with licensure of the product. An annual stability program helps assure continued quality of product throughout the dating period, while comparability studies are performed after a process or facilities change in order to demonstrate that the change has not impacted the stability characteristics of the product. Careful attention to the design and analysis of post licensure studies helps mitigate the risk of missing a meaningful shift in the degradation rate of a vaccine, as well as the possibility of incorrectly earmarking a stability shift when the product remains acceptable.