In some specific cases, testing of a product or device in its intended operating environment may also be required to demonstrate that a product meets all prequalification requirements. Field testing is required, for example, for products that include technology not previously used in health programmes in low-resource settings, or that require the creation of a new category of products for prequalification.
Field testing provides manufacturers with information to further improve product design and it can also help end users to choose products that are best suited to their needs. Field testing is carried out by the product manufacturer with the support of testing laboratories and in accordance with protocols established by WHO. Also essential is the active cooperation of national EPI programme managers and the assistance of technical staff in WHO/UNICEF country and regional offices.