WHO vaccines prequalification works to ensure that a sufficient supply of safe, effective vaccines is available for immunization programmes, including in emergency situations and in response to novel disease outbreaks. It:

• applies WHO-established standards and norms of acceptable quality, safety and efficacy
• assesses vaccines for prequalification via a rigorous process of evaluation
• considers Member States’ demand, and programmatic needs and supply security
• enforces adherence to good manufacturing processes (GMP), good clinical practice, and the operational packaging and presentation requirements of the relevant procurement agencie(s)
• requires the observance of stringent post-prequalification requirements in order to ensure continuous vaccine quality
• investigates all reports of quality complaints related to vaccines in use by national immunization programmes
• helps to stimulate a healthy and competitive marketplace for vaccines by collaborating with national regulatory authorities and control laboratories.

The norms and standards that underpin WHO vaccines prequalification are developed and adopted by the WHO Expert Committee on Biological Standardization. These cover vaccine standards that address the manufacturing, licensing, quality control, labelling, transportation and storage of vaccines. Investigation of safety-related vaccine complaints (AEFIs) is carried out together with WHO colleagues working in the area of vaccines safety, while work to support vaccines regulatory strengthening is part of broader support provided by WHO to national regulatory authorities (NRAs). The NRAs of vaccines-exporting countries, and their testing laboratories, play an important role in the prequalification process.

Assessment

WHO vaccines prequalification may assess any vaccine that is a WHO priority. The responsible NRA must have been confirmed — through assessment using the WHO Global Benchmarking Tool (GBT) — as having the required "maturity level". Standard evaluation of a vaccine includes review of the manufacturing process, verification of compliance with relevant standards, sample lot testing and a site audit. Procedures are also in place to ensure a standardized approach for streamlined and expedited assessment, including reliance on the responsible NRA. In addition, provisions for emergency use and listing have been developed, to ensure vaccine availability during public health emergencies. Moreover, vaccines prequalification contributes to innovation when a compelling unmet public health need is established, by providing technical support to vaccine manufacturers in collaboration with other organizations and networks.

Ensuring that the quality of prequalified vaccines is maintained

Vaccines prequalification applies comprehensive ongoing requirements, stipulated by the WHO, to ensure that the prequalification endorsement of the performance, efficacy and safety of a vaccine remains valid. In addition, periodic reassessment of all prequalified vaccines is carried out, based on quality risk management principles. This includes annual testing of sample lots and evaluation of their associated summary release protocols, and NRA/national control laboratory batch release certificates. Lastly, all post-prequalification product changes are reviewed, based on information supplied by product manufacturers, as a part of the comprehensive annual review requirement. WHO may revoke or suspend the prequalified status of a vaccine if a manufacturer fails to fully comply with one or more of the post-prequalification requirements, or reports of serious quality defects or safety-related complaints have been received.

Collaboration with NRAs

WHO vaccines prequalification works with NRAs that have been recognized as having a sufficient level of "maturity", according to WHO's GBT. NRAs play a vital role in regulatory oversight of vaccines intended for use in national immunization programmes. In some cases, WHO may agree to sign collaborative agreements or enter into a collaborative arrangement with certain NRAs whereby the prequalification process will be shortened or streamlined through WHO reliance on the NRA’s assessment, testing and inspection reports.