Twice each year influenza experts gather to discuss recent developments in human and animal influenza viruses around the globe, and to decide on the composition of the next influenza season’s flu vaccine.
Due to the time it takes to manufacture a vaccine, decisions on which strains to include must be made six months in advance.
The composition of the northern hemisphere’s vaccine is decided upon in February of each year, and decisions on the southern hemisphere’ vaccine are made in September.
Recently (Sept 17-19) participants from divisions of the World Health Organization’s GISRS (Global Influenza Surveillance and Response System), along with members of OFFLU (the OIE/FAO Network on Animal Influenza), and other experts met in Beijing, China to discuss and decide on the formulation for next year’s vaccine in the Southern Hemisphere.
For those of us in the Northern Hemisphere the news is encouraging, as recommendations for next year south of the equator match our current vaccine formulation, that was decided upon last February.
Their discussions and recommendations may be found in the 16 page PDF document:
Here is the bottom line from the document:
It is recommended that trivalent vaccines for use in the 2013 influenza season (southern hemisphere winter) contain the following:
- an A/California/7/2009 (H1N1)pdm09-like virus;
- an A/Victoria/361/2011 (H3N2)-like virus;
- a B/Wisconsin/1/2010-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.
Of particular note is the switch from a Victoria lineage Influenza B virus to a Yamagata- Lineage strain. While both lineages have been circulating over the past year, the Yamagata strain is perceived to be on the ascendant, and as it has not been included in the vaccine for several years, community immunity is likely low.
Regular readers of this blog are aware that over the past year we’ve seen An Increasingly Complex Flu Field, with the recent uptick in swine variant flu cases (H3N2v, H1N2v, & H1N1v) across North America.
Additionally, sporadic cases of avian influenza strains (H5N1, H5N2, H7’s, H9N2, and H3N8) continue to be reported around the globe.
The report noted these zoonotic viruses by saying:
From 23 February to 18 September 2012, 17 confirmed human cases of A(H5N1), 10 of which were fatal, were reported by Bangladesh, Cambodia, China Hong Kong Special Administrative Region, Egypt, Indonesia, and Viet Nam where highly pathogenic avian influenza A(H5N1) is present in poultry and/or wild birds. Since December 2003, a total of 608 cases with 359 deaths have been confirmed in 15 countries.
To date there has been no evidence of sustained human-to-human transmission. Human cases of influenza A(v) viruses have been detected since February 2012 in the United States of America where a total of 305 infections caused by A(H3N2)v viruses have been reported. One of these infections was fatal. A single case of A(H1N1)v and three cases of A(H1N2)v have also been detected.
Two human cases of conjunctivitis due to A(H7N3) have been reported by Mexico. Both cases had exposure to A(H7N3) infected poultry.
No human cases of influenza A(H9N2) were detected during the period 23 February to 18 September 2012.
We won’t know how well this decision will turn out in the southern hemisphere for another 6 to 12 months, but for those of us north of the equator, this is a pretty good indication that confidence in the makeup of this fall’s flu vaccine remains high.
A good enough reason to go ahead and get the shot this year, before flu season arrives.