Potency testing of diphtheria and tetanus toxoids. A reliable, pragmatic and economic approach.

The aim of potency testing is to ensure that vaccines under test will provide protection when used in human subjects. To achieve this, many potency tests for diphtheria and tetanus toxoids have been devised. the potency tests listed in the European Pharmacopoeia and the W.H.O. Requirements call for the use of large numbers of either guinea pigs or mice. These quantal assays are extremely expensive to perform and alternative, more economic methods are clearly needed. The results presented here illustrate that, provided certain rules are followed single point assays can provide the same degree of assurance of potency as the three-point assays currently in use.