Credit NIAID
# 8314
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. 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 the northern hemisphere’s vaccine must be decided upon in February of each year, while decisions on the southern hemisphere’ vaccine are made in September.
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.
Of course, there is always the danger that during the manufacturing or service period for this vaccine a new flu virus could emerge (as happened with pH1N1 in 2009), or that one of the currently circulating viruses changes enough antigenically to evade the vaccine. A year is a long time to prognosticate the behavior of influenza.
Yet despite these challenges, most years the flu vaccine turns out to provide at least a moderate level of protection (see CDC Vaccine Effectiveness - How Well Does the Flu Vaccine Work?), and along with good flu hygiene (washing hands, covering coughs, etc.), are your best protection against catching the flu.
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 determine the recommended composition of influenza virus vaccines for use in the 2014-15 northern hemisphere influenza season.
After reviewing copious influenza surveillance reports, the committee has recommended keeping the same formulation as was adopted last February for the 2013-14 flu season, and for the upcoming 2014 Southern Hemisphere flu season (see WHO: Southern Hemisphere 2014 Flu Vaccine Composition).
20 February 2014
It is recommended that trivalent vaccines for use in the 2014-15 influenza season (northern hemisphere winter) contain the following:
- an A/California/7/2009 (H1N1)pdm09-like virus;
- an A/Texas/50/2012 (H3N2)-like virus;
- a B/Massachusetts/2/2012-like virus.
It is recommended that quadrivalent vaccines containing two influenza B viruses contain the above three viruses and a B/Brisbane/60/2008-like virus.
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