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WHO Recommendation on influenza virus vaccines for the Northern Hemisphere 2013-2014 season

15 Mar 2013
On 21 February 2013, WHO issued its recommendation for the composition of influenza vaccines for the 2013-2014 influenza season in the northern hemisphere. A short headline report on the vaccine recommendations for next season is available as well as a more detailed report which also contains information on the antiviral resistance and the laboratory-assessed match between this season’s vaccine and circulating viruses. (1,2)
The recommendations are that for trivalent vaccines for use in the 2013-14 influenza season (Northern Hemisphere winter) contain the following:
  • For A(H1N1) an A/California/7/2009 (H1N1)pdm09-like virus;  the same as during the current 2012-13 season;
  • For A(H3N2) an A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011+;
  • For B/Yagamata a B/Massachusetts/2/2012-like virus for the B/Yagamata lineage a change from the . B/Wisconsin/1/2010-like virus in 2012-2013.


  • It is recommended that any quadrivalent vaccines containing two influenza B viruses also contain a B/Brisbane/60/2008-like virus for the B/Victoria lineage.

Producing these recommendations in its biannual influenza vaccine strain selection meetings is an important function of the laboratory aspect of the Global Influenza Surveillance and Response System (GISRS) coordinated by WHO. These scientific meetings take place around February and September each year and make respectively make recommendations on the antigens to be used in the influenza vaccines for the coming Northern Hemisphere (February meetings) and Southern Hemisphere seasons (September meetings). (3,4)  
The objectives of these meetings are to:
  • Analyse the antigenic and genetic characteristics of influenza viruses circulating and infecting humans, taking into consideration of available epidemiological and clinical information from individual countries and regions;
  • Make recommendations on the composition of the influenza vaccines for use in the northern and southern hemisphere - in this case for the 2013-2014 northern hemisphere season;
  • Review the antigenic and genetic characteristics of recent A(H5N1) viruses that the WHO Collaborating Centres of the GISRS received and the need to develop new A(H5N1) candidate vaccine viruses for pandemic preparedness purposes;
  • Review the antigenic and genetic characteristics of other subtype or variant influenza viruses, if any, infecting humans recently, and the need to develop new candidate vaccine viruses for pandemic preparedness purposes.
The meeting represents the end point of an intense period of work for National Influenza Centres who contribute viruses and detailed virological data to WHO’s six global influenza Collaborating Centres and four Essential Regulatory Laboratories  who undertake more complex antigenic and genetic analyses.(1-4)  Scientists from centres and laboratories look carefully at the data from all across the world with the prime purpose of seeing how well the influenza viruses that have been circulating match the currently used vaccine antigen strains. This is with a view to whether there are other strains more suitable for vaccine production as they match the circulating viruses more closely when they are in use in vaccines. These discussions are undertaken privately.  After a conclusion has been taken, the information is communicated to industry, regulators and other interested parties at an open session in Geneva. These recommendations are then taken for further formal decisions by regulators and industry with the decisions for Europe being overseen by the European Medicines Agency and the European Commission.
ECDC Comments:  14/03/2013
It is important to appreciate the intense scientific and administrative work that goes into this biannual process by National Influenza Centres, the WHO Collaborating Centres and the Essential Regulatory Laboratories.
The move towards manufacturers having quadrivalent  vaccines was already noted last year. There are clinical advantages in covering both B/Victoria and B/Yagamata lineages, however, this innovation may drive up the unit cost of vaccines and the cost benefit may not be great. This current season, for instance, the previously uncovered B/Victoria viruses represent only 10% of all sub-typed B viruses among sentinel samples and hence only 5% of all influenza viruses. See WISO Week 9/2013 
For the first time the WHO meeting formally received a compilation of the preliminary vaccine effectiveness estimates for this season. These were compiled into a report for the meeting by Epiconcept for the I-MOVE collaboration, ECDC, CDC and Canadian researchers. The European estimates for the 2012-2013 are listed below.(5-9)  A welcome change this year has been an increase in vaccine effectiveness compared to the very low levels observed in 2011-2012, as shown, for example, in the early estimates of the I-MOVE based studies in 2011/2012 and 2012/2013.(8,10,11) It remains the case that influenza vaccines are sub-optimal in their effectiveness while at the same time they represent the best single way of providing protection against influenza infection and disease.(12)    
+ For the A(H3N2) vaccine component:  while the WHO lead experts noted that circulating viruses still had antigenic properties like the A/Victoria/361/2011-cell propagated virus, they recommended a change in the actual virus used to A/Texas/50/2012. This is due to the fact that when the A/Victoria/361/2011 viruses were propagated in eggs important antigenic changes appeared. When A/Texas/50/2012 is used the required antigenic properties are retained in both cell and egg-propagated antigens. See the European virological report (4) and the detailed WHO report to explain this further.


1. WHO  Recommended composition of influenza virus vaccines for use in the 2013-2014 northern hemisphere influenza season February 2013

2. European Influenza virus characterisation report,  February 2013

3. Gerdil C. The annual production cycle for influenza vaccine. Vaccine 2003; 21: 1776-9

4. WHO Process of influenza vaccine virus selection and development. November 2007

5. McMenamin J, Andrews N, Robertson C, Fleming DM, Durnall H, von Wissmann B, Ellis J, Lackenby A, Cottrell S, Smyth B, Zambon M, Moore C, Watson JM, Pebody RG. Effectiveness of seasonal 2012/13 vaccine in preventing laboratory-confirmed influenza infection in primary care in the United Kingdom: mid-season analysis 2012/13. Euro Surveill. 2013;18(5):pii=20393. Available online:

6. Bragstad K, Emborg HD, Kølsen Fischer T, Voldstedlund M, Gubbels S, Andersen B, Mølbak K, Krause TG. Low vaccine effectiveness against influenza A(H3N2) virus among elderly people in Denmark in 2012/13 – a rapid epidemiological and virological assessment. Euro Surveill. 2013;18(6):pii=20397. Available online:

7. Castilla J, Martínez-Baz I, Martínez-Artola V, Fernandez-Alonso M, Reina G, Guevara M, García Cenoz M, Elía F, Alvarez N, Barricarte A, Ezpeleta C. Early estimates of influenza vaccine effectiveness in Navarre, Spain: 2012/13 mid-season analysis. Euro Surveill. 2013;18(7):pii=20404. Available online:

8. Valenciano M, Kissling E, I-MOVE case–control study team. Early estimates of seasonal influenza vaccine effectiveness in Europe: results from the I-MOVE multicentre case–control study, 2012/13 . Euro Surveill. 2013;18(7):pii=20400. Available online:

9. van der Hoek W, Dijkstra F, de Lange MM, Donker GA, Meijer A, van der Sande MA. Letter to the editor: Influenza vaccine effectiveness: heterogeneity in estimates for the 2012/13 season. Euro Surveill. 2013;18(7):pii=20399. Available online:

10. Kissling E, Valenciano M, I-MOVE case–control studies team. Early estimates of seasonal influenza vaccine effectiveness in Europe among target groups for vaccination: results from the I-MOVE multicentre case–control study, 2011/12. Euro Surveill. 2012;17(15):pii=20146. Available online:

11. Kissling E, Valenciano M, Larrauri A, Oroszi B, Cohen JM, Nunes B, Pitigoi D, Rizzo C, Rebolledo J, Paradowska-Stankiewicz I, Jiménez-Jorge S, Horváth JK, Daviaud I, Guiomar R, Necula G, Bella A, O’Donnell J, Głuchowska M, Ciancio BC, Nicoll A, Moren A. Low and decreasing vaccine effectiveness against influenza A(H3) in 2011/12 among vaccination target groups in Europe: results from the I-MOVE multicentre case–control study . Euro Surveill. 2013;18(5):pii=20390. Available online:

12. Nicoll A, Sprenger M. Low effectiveness undermines promotion of seasonal influenza vaccine  Lancet Infectious Diseases, Volume 13, Issue 1, Pages 7 - 9, January 2013  doi:10.1016/S1473-3099(12)70313-4

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