Overcoming scientific barriers in the transition from to non-animal batch testing of human and veterinary vaccines.

Introduction: Before release, vaccine batches are assessed for quality to evaluate whether they meet the product specifications. Vaccine batch tests, in particular of inactivated and toxoid vaccines, still largely rely on methods. Improved vaccine production processes, ethical concerns, and suboptimal performance of some tests have led to the development of alternatives.

Areas Covered: This review describes the scientific constraints that need to be overcome for replacement of batch tests, as well as potential solutions. Topics include the critical quality attributes of vaccines that require testing, the use of cell-based assays to mimic aspects of vaccine-induced immune responses, how difficulties with testing adjuvanted vaccines can be overcome, the use of altered batches to validate new test methods, and how cooperation between different stakeholders is key to moving the transition forward.

Expert Opinion: For safety testing, many alternatives are already available or at an advanced level of development. For potency testing, alternatives largely comprise immunochemical methods that assess several, but not all critical vaccine properties. One-to-one replacement by alternatives is not always possible and a combination of methods may be required.