Availability of H5N1 prototype strains for influenza pandemic vaccine development

February 2005

The WHO Influenza Surveillance Network has characterized H5N1 influenza viruses isolated from humans and animals from several countries affected by the 2004/2005 H5N1 outbreak in Asia. WHO has also made recommendations on the antigenic and genetic characteristics of H5N1 viruses which are suitable for vaccine production.

In addition, WHO collaborating centres and reference laboratories have developed several recombinant H5N1 prototype vaccine strains, including A/Vietnam/1194/04, A/Vietnam/1203/04 and A/Hongkong/213/03, according to the requirements of several major national and international pharmaceutical licensing agencies for influenza vaccine production. These H5N1 influenza pandemic vaccine prototype strains have already been made available to a number of institutions and companies and several different vaccines have been produced for clinical testing.

It is understood that there are no intellectual property issues restricting the use of reverse genetics for pandemic vaccine research. However it is anticipated that licences must be negotiated before commercial use of such vaccines.

In some countries, the reassortant may be viewed as a genetically modified organism and approval will be needed for virus cultivation. Also in some countries, although the reassortant is derived from a human H5N1 virus, it may be subject to an import licence from veterinary authorities.

Influenza vaccine manufacturers who wish to receive these prototype strains should contact either the WHO Global Influenza Programme at or any of the institutions below:

  • National Institute for Biological Standards and Control, Blanche Lane, South Mimms, Potters Bar, Hertfordshire EN6 3QG, England (fax: +44 1707 646730; e-mail:
  • WHO Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Centers for Disease Control and Prevention, 1600 Clifton Road, Mail stop G16, Atlanta, GA 30333, USA (fax: +1 404 639 23 34; e-mail:
  • WHO Collaborating Center for Studies on the Ecology of Influenza in Animals, St Jude Children's Research Hospital, 332 North Lauderdale St., Memphis, TN 38105-2794 USA (fax: +1 901 523 2622; e-mail:

Questions or requests for additional information should be addressed to WHO at