Immunization standards

A system for the prequalification of vaccines for UN supply

WHO provides a service to UNICEF and other UN agencies that purchase vaccines, to determine the acceptability, in principle, of vaccines from different sources for supply to these agencies. The detailed procedure can be found at the link below.

There is an established procedure used by WHO for the initial evaluation of candidate vaccines. Reassessment at regular intervals ensures the continuing quality of vaccines.

The revised prequalification procedure was reviewed and endorsed by the WHO Expert Committee on Biological Standardization in October 2010 and is published in WHO TRS 978, Annex 6 .
(effective date: February 2012)

Key elements of the procedure are:


  • Vaccines used in immunization programmes are safe and effective.
  • Vaccine efficacy data and studies are relevant to the target population.
  • Vaccines meet the specific needs of the programme, reflected by the tender specifications: i.e. potency, thermostability, presentation, labeling, shipping conditions, etc.


  • Reliance on the National Regulatory Authority responsible for the regulatory oversight of the vaccine.
  • Understanding of production process and quality control (QC) methods.
  • Production consistency ensured through good manufacturing practices (GMP) compliance.
  • Testing for compliance with specifications.
  • Monitoring of complaints from the field.


  • The National Regulatory Authority responsible for the product is "functional" as per assessment performed using the WHO established indicators.


  • Review of general production process and quality control procedures.
  • Testing of consistency of lots.
  • WHO site audit to manufacturing facilities with observers from the responsible National Regulatory Authority.

Assurance of continued acceptability

  • Reassessments at regular intervals.
  • Targeted testing programme of lots supplied through UN agencies to monitor continued compliance with specifications.
  • Follow up of complaints from the field and reports of adverse events following immunization (AEFI).

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Last update:

5 September 2017 10:37 CEST


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