Why isn't there a vaccine yet?
Producing a vaccine is difficult. Any vaccine produced needs to closely match the pandemic virus, and that virus will be a mutation from the current strains of H5N1. Viruses are known for their mutations. Even with the production of a vaccine specifically tailored to a pandemic virus, further mutations could make such a vaccine ineffective. Vaccines that are produced for seasonal influenza will not protect against a bird flu pandemic influenza.
Many countries are working to develop a vaccine for H5N1, but none is yet proven effective for humans. Moreover, even if such a vaccine becomes available, it will not be ready for commercial production until several months after the start of a pandemic. According to the World Health Organization (WHO), current global production capacity falls far short of the amount of vaccine that would be needed to deal with a pandemic.
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