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Twice each year influenza experts gather to discuss recent developments in human and animal influenza viruses around the world, and to decide on the composition of the next influenza season’s flu vaccine.
NIAID has a terrific 3-minute video that shows how influenza viruses drift over time, and why the flu shot must be frequently updated, which you can view at this link.
Due to the time it takes to manufacture and distribute a vaccine, decisions on which strains to include must be made six months in advance, Which means the composition of next fall's northern hemisphere’s vaccine must be decided upon in late February.
This week the World Health Organization brought together representatives from GISRS (Global Influenza Surveillance and Response System), along with members of OFFLU (the OIE/FAO Network on Animal Influenza), and other experts to recommend what flu strains to include in next fall's vaccine.
- After a remarkable eight year reign, the original A/California/7/2009-like H1N1 strain has been retired, and replaced with an A/Michigan/45/2015 (H1N1)pdm09-like virus, which has already been incorporated into this year's Southern Hemisphere vaccine.
- The H3N2 component - a perennial `problem child' for vaccine producers - remains unchanged from last year (A/Hong Kong/4801/2014 (H3N2)-like virus), despite growing diversity among this subtype (see Eurosurveillance: Emergence Of A Novel Subclade Of Seasonal A/H3N2 - London).
- And the primary B component remains the same as last year; a B/Brisbane/60/2008-like virus, which also matches this year's Southern Hemisphere vaccine. The secondary B (for use in a quadrivalent vaccine) remains unchanged as well; a B/Phuket/3073/2013-like virus.
The WHO announcement, and link to the full report follow.
2 March 2017
It is recommended that trivalent vaccines for use in the 2017-2018 northern hemisphere influenza season contain the following:
It is recommended that quadrivalent vaccines containing two influenza B viruses contain the above three viruses and a B/Phuket/3073/2013-like virus.
- an A/Michigan/45/2015 (H1N1)pdm09-like virus;
- an A/Hong Kong/4801/2014 (H3N2)-like virus; and
- a B/Brisbane/60/2008-like virus.
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