Scientists have used bird flu virus samples from Egypt to develop a new basis for a vaccine against the toxic H5N1 strain that continues to circulate, the World Health Organization said.
The WHO said the candidate virus was developed at the US Centres for Disease Control and Prevention in Atlanta "thanks to the ministry of health and population of Egypt, for providing virus specimens".
"This recombinant vaccine virus is available for distribution," it said in a statement. "Institutions, companies and others interested in pandemic vaccine development who wish to receive these candidate vaccine viruses should contact either the WHO Global Influenza Program ... or the Centres for Disease Control and Prevention."
Pharmaceutical companies including Novartis are already working on vaccines against H5N1 bird flu, which has killed or forced the culling of more than 300 million birds since 2003 as it spread to 61 countries in Asia, the Middle East and Africa.
The U.N.'s Food and Agriculture Organization reported 250 outbreaks of H5N1 in birds in February alone -- in Bangladesh, China, Egypt, India, Indonesia, Laos, Nepal and Vietnam.
Avian influenza has killed 261 people out of 424 infected since 2003.
Its statement on said flu experts were continuing to monitor the evolution of avian influenza and other flu viruses and stressed the need for countries to keep providing samples of identified strains.
"Countries are encouraged to share with WHO their specimens and/or isolates, both from humans and animals, for their inclusion in the WHO H5N1 vaccine virus development and selection process, in addition to other activities of public health significance," it said.