The hunt for a good bird flu vaccine to be used in humans has gone on for some 10 years, since the H5N1 family of avian flu first emerged in Hong Kong, said the author of a perspective accompanying this latest study, both published in the June 12 issue of the New England Journal of Medicine.
In the past two years, the H5N1 strain of avian flu has infected poultry throughout Southeast Asia, Central Asia, Africa and Europe, prompting the destruction of millions of birds. So far, more than 100 people have died worldwide from H5N1 infection, which has been spread through close contact with birds.
Experts fear that the virus will acquire the ability to jump easily between humans, leading to a pandemic and millions of deaths. Unlike the seasonal flu, humans have no immunity to bird flu.
Last year, the U.S. Food and Drug Administration approved an admittedly less-than-perfect vaccine against bird flu, the first such vaccine to be approved for humans. At the time, the vaccine was described as an "interim measure."
Producing and distributing enough vaccine to protect large populations is a key problem.
For the past 50 years, vaccines have been made using a cumbersome egg-based technology, which requires weakened virus injected into hundreds of millions of fertilized hens' eggs each year. The process takes about six months to be completed and has to be repeated as virus strains change.
The Vero cell technology used here uses "wild type" virus (the strains existing in nature) grown directly in cell culture, allowing more of the vaccine to be produced in a
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