Immunization standards

WHO contracted laboratories performing tests on behalf of the WHO vaccine prequalification programme

In 2010 the prequalification programme for vaccines has undergone a substantial revision process following the recommendations of the ad hoc committee on vaccines prequalification. One of the changes introduced was the decision to publish on the website the list of laboratories contracted by WHO to perform tests on behalf of the prequalification programme.

The independent testing of vaccines is part of the procedure for evaluation of the acceptability, in principle, of vaccines for purchase by United Nations agencies. The testing is performed to assess the consistency of final product characteristics and represents one of the decision making criteria for granting prequalification. Tests undertaken are the most relevant to reflect the quality, safety and efficacy of the vaccines. Usually potency and toxicity are tested. However, depending on the nature of the vaccines, other relevant tests can be performed. A targeted testing strategy is followed. Vaccines are expected to comply with WHO recommended requirements as well as with the UN tender specifications.

Once the vaccines are prequalified, there is continual monitoring for compliance with the established specifications through regular testing of lots of vaccine that have been shipped to countries. For this purpose, manufacturers are required to keep aside, pending request from WHO, samples of each of the vaccine lots shipped to countries through the UN procuring agencies.

Independent testing may also be required on occasions in response to complaints from the field or following reports of adverse events following immunization (AEFI) when a quality problem is suspected.

Moreover, occasionally countries that procure vaccines, either directly or through the UN system, may need to test vaccines for different reasons and require access to laboratories that are accredited to perform specific tests for vaccines.

Laboratories considered for independent testing are subject to evaluation of performance. Such evaluation includes the following steps:

  • assessment of the documentation relative to the proposed testing methodologies,
  • testing of lots of vaccine in parallel with other already qualified contracted laboratories
  • on site assessment of the quality systems in place.

Different laboratories are evaluated and further contracted for specific tests for which they offer the service. Not all laboratories are qualified by the WHO vaccines prequalification programme to perform all tests. The fact that certain laboratories/certain tests are not included on the list does not mean that if evaluated, such laboratories would not be found to comply with the required standards for testing.

WHO recognizes the certification of laboratories by international accreditation organisms and in such cases may waive the on site assessment of the laboratory.

The publication of the list of qualified laboratories contracted by WHO for specific tests is important for transparency reasons, to recognize the work performed by these laboratories in a collaborative effort with WHO and also to give access to this information to countries that can become occasional users.

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Last update:

28 May 2012 16:22 CEST