Approaches to reducing animal numbers in vaccine potency testing

Vaccine potency testing is conducted to provide manufacturers and regulatory officials information regarding the potency of vaccine products prior to market release. Post-licensing potency test protocols are often described and incorporated into regulation or guidance documents. This provides manufacturers with a consistent and uniform framework to follow for market release. Some of these protocols are based on widely accepted international test methods; others have been in existence for decades and were based on the best scientific information available at that time. In an effort to ensure that vaccine testing conducted on live animals provides optimal animal welfare, alternative test methods incorporating reduction, replacement, and refinement techniques should be considered and used when appropriate. Russell and Burch, in The Principles of Humane Experimental Technique, define reduction as “reduction in the numbers of animals used to obtain information of a given amount and precision.” This paper will focus on three methods of reducing the number of animals used for potency testing. These reduction methods include (1) a change in experimental design, (2) a change based on statistical review, and (3) changes resulting from the harmonization of test requirements.