The U.N. World Health Organization and the U.S. Centers for Disease Control and Prevention are already working with samples of the new H7N9 bird flu virus in China to make a vaccine, if one is needed.
The following are some key facts about vaccines, drugs and avian influenza:
* The WHO and CDC prepare samples of the virus to give to industrial manufacturers.
* These samples are usually grown in chicken eggs from which the virus is purified and made into vaccines, a process requiring many months for organization of egg supplies, virus incubation and actual production.
* New cell-culture technology developed by Novartis AG NOVN.VX has reduced this production timeline to a matter of weeks, although human safety trials still take several months.
* Major flu vaccine manufacturers include Sanofi SA (SASY.PA), GlaxoSmithKline Plc (GSK.L), Novartis, Australia's CSL Ltd (CSL.AX), Baxter International Inc (BAX.N) and AstraZeneca Plc (AZN.L), which makes a nasal spray vaccine rather than an injection.
* The first cases of this new strain of bird flu, officially called avian influenza A (H7N9) virus, were reported by the World Health Organization in late March.
* Type A flu viruses occur naturally among wild birds and can infect domestic poultry and other bird and animal species, but they rarely infect humans and have typically occurred when people have had close contact with poultry, as with the H5N1 bird flu outbreak.
* The two main drugs that appear to work against the new H7N9 flu strain are Roche Holding AG's ROG.VX Tamiflu and GlaxoSmithKline's Relenza.
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(Reporting by Ben Hirschler and Julie Steenhuysen; Editing by Phil Berlowitz)