WHO assesses the performance, quality and safety characteristics of prequalified products throughout their life cycle according to defined standards. It also evaluates product's suitability for identified programmatic and operational needs and challenges. Prequalified products are reviewed annually via the Annual Review of IMD-PQS prequalified products, and throughout the year, based on field performance feedback.

Occasionally, circumstances may arise that dictate emergency re-evaluation; for example, WHO has received reports of serious product failure. In such cases, WHO may suspend or remove a product from the WHO List of Prequalified Immunization Devices if circumstances warrant such action. Alternatively, Prequalification-holders may decide to request that a product be removed from the prequalified list; for example, if the product is discontinued.

An up-to-date list of products withdrawn from the WHO IMD-PQS database is provided below. These products became ineligible for procurement by UN procurement agencies from the withdrawal date indicated.