Alternative tests have a role in vaccine testing, especially to confirm production consistency. Given the characteristics of these alternative tests and of the products for which they may be used, there are several factors which will influence their use. These include a good understanding of the test and the product to be tested, strong national regulatory infrastructure, a laboratory run in accordance with the principles of laboratory quality systems, and the ability to validate the alternative method. This means that national regulatory authorities will need strong expertise in epidemiology and quality assurance to complement laboratory experience.