By using samples of the H5N1 (avian flu) virus obtained from Egypt, CDC scientists have developed a virus sample critical to the production of a bird flu vaccine, the WHO said Thursday, Reuters reports.

Though the H5N1 virus does not spread easily via human-to-human transmission as the H1N1 (swine flu) virus does, the H5N1 virus has proven more deadly, killing 261 of the 424 people infected since 2003 (MacInnis, Reuters, 5/28). The Ministry of Health of Egypt on Tuesday confirmed two new human cases of avian flu, the WHO reports (Avian Influenza – situation in Egypt – update 17, 5/28). In February, there were more than 250 confirmed outbreaks of H5N1 in birds in Bangladesh, China, Egypt, India, Indonesia, Laos, Nepal and Vietnam, according to the U.N.’s Food and Agriculture Organization.  

“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,” Reuters writes.

In a statement, the WHO encouraged countries to share H5N1 virus samples with the organization for “their inclusion in the WHO H5N1 vaccine development and selection process, in addition to other activities of public health significance” (Reuters, 5/28). A two-day intergovernmental WHO meeting held earlier this month ended without a final international virus-sharing agreement (Kaiser Global Health Policy Report, 5/18).