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Rethinking the Ingredients of Influenza Vaccines for 2010

Next winter in the Southern Hemisphere, influenza vaccines should no longer be designed to protect against the seasonal H1N1 strain as the pandemic H1N1 strain has replaced it, according to World Health Organization (WHO) recommendations issued today.

As the recommendations explain, the seasonal strain has caused few outbreaks since the discovery of the swine flu strain last April.

WHO thus is recommending that vaccine makers drop the seasonal H1N1 virus from formulations that also contain an H3N2 strain and a type B, Brisbane strain. One possibility is that vaccine makers will simply replace the dropped virus with the pandemic H1N1 strain in a new trivalent product. Or countries may decide to use a monovalent vaccine that protects against the pandemic strain and a bivalent product designed to work against H3N2 and the Brisbane strain. WHO’s Strategic Advisory Group of Experts will debate these issues when it meets in late October. WHO will not make recommendations for the next Northern Hemisphere flu vaccines until February of next year.

(This item was originally titled "WHO Simplifies Flu Vaccine for Sourthern Hemiphere" and has been corrected.)