WHO produces five principle types of guidance documents for manufacturers seeking prequalified of an immunization devices and laboratories pursuing accreditation:

• guidance to manufacturers and suppliers of each category of cold chain-related products: prequalification guidelines that explain how to apply for prequalification and how to maintain prequalification status
• performance specifications: published standards which set out the detailed performance requirements for an immunization-related product. They define the functional requirements of a product and describe the environment within which it must operate.
• verification protocols: describe in detail how the performance of a product or device will be tested or otherwise evaluated as part of the product prequalification process. Each performance specification is accompanied by at least one corresponding verification protocol.
• target product profiles (TPPs): strategic documents that contain a detailed description of desirable future product characteristics, features or functions. They explain the reason for each desirable characteristic and may state the date by which the feature is scheduled to be included in the specification and become a requirement for prequalification.
• standard operating procedures (SOPs): ensure that all tasks related to prequalification of immunization products are carried out consistently and systematically. This prequalification process consists of six major tasks: writing and revising performance specifications; writing and revising product verification protocols; accrediting testing laboratories; prequalifying and re-evaluatin products; field testing these products and obtaining product feedback from users.

Product manufacturers wishing to apply for prequalification, as well as testing laboratories pursuing accreditation, should consult the relevant performance specifications and verification protocols to enable them to fully complete their applications for evaluation for prequalification or accreditation.

Product manufacturers are also encouraged to consult the TPPs since these will inform them about desirable future product characteristics, features or functions.

All partners and stakeholders are encouraged to consult the SOPs relevant to their operations as part of the process of familiarizing themselves with WHO prequalification procedures.

These guidance documents are developed by WHO in collaboration with national immunization programmes, industry manufacturers, accredited testing laboratories and a range of technical specialist organizations.

Standards development and revision

Development and revision of specifications. WHO is committed to maintaining product specifications and protocols through a process of review, quality enforcement and, when required, revision based on:

• product field-testing
• ongoing user-feedback on product performance in the operating environment
• manufacturer feedback on root causes of any product challenges as part of the annual review
• industry innovations and other improvements of relevant technologies.