Sunday, September 30, 2012

A Research Project on the H3N2 strain that's part of this years Seasonal Flu Shot

These are snippets regarding the H3N2 strain that is incorporated in this years Seasonal Vaccine (flu shot).  It is not to be confused with the H3N2v, which you can read up on, from documents located on the right side-bar.  All editing below is mine.

FDA U.S. Food & Drug Administration News Release:

FDA approves vaccines for the 2012-2013 influenza season

The U.S. Food and Drug Administration announced today that it has approved the 2012-2013 influenza (flu) vaccine formulation for all six manufacturers licensed to produce and distribute the vaccines in the United States.
Each year experts from the FDA, the World Health Organization, the Centers for Disease Control and Prevention (CDC), and other public health experts study influenza virus samples and global disease patterns to identify virus strains likely to cause the most illness during the upcoming flu season.
Based on that information and the recommendations of the FDA’s Vaccines and Related Biological Products Advisory Committee, the strains selected for inclusion in the 2012-2013 flu vaccines are:
  • A/California/7/2009 (H1N1)-like virus
  • A/Victoria/361/2011 (H3N2)-like virus
  • B/Wisconsin/1/2010-like virus.
The manufacturers licensed to produce the nation’s 2012-2013 flu vaccines and the brand names of the vaccines for the upcoming flu season are:
  • Afluria, manufactured by CSL Limited;
  • Fluarix, manufactured by GlaxoSmithKline Biologicals;
  • FluLaval, manufactured by ID Biomedical Corporation;
  • FluMist, manufactured by MedImmune Vaccines Inc.;
  • Fluvirin, manufactured by Novartis Vaccines and Diagnostics Limited; and
  • Fluzone, Fluzone High-Dose and Fluzone Intradermal, manufactured by Sanofi Pasteur.
The H3N2 information starts on Slide 18 of 65

Influenza A(H3N2) virus activity, September 2011 - January 2012 (posted 17 February 2012)

page 37:

And lastly, this piece from the Clinical Virology Symposim, April 2012:

Wendy Sessions, Angie Foust, Lizheng Guo, Rebecca Garten, John Barnes, Kyung Park, Elisabeth Blanchard, Teresa Wallis, Henrietta Hall, Thomas Rowe, Jan Mabry, Alexander Klimov, and Xiyan Xu 
Virus Surveillance and Diagnosis Branch, Influenza Division, Centers for Disease Control and Prevention 
Influenza A H3N2 viruses first appeared in humans in 1968 and since then have co-circulated along with influenza A H1N1 (seasonal or pdm09) and influenza B.  The H3N2 subtype has been associated with significant morbidity and mortality compared to the other human influenza viruses.  During the 2011-2012 influenza season, influenza A H3N2 has been the dominant subtype circulating in the United States although, as of February, activity has remained low.  This differs from the previous season, when H3N2 was the predominant virus however influenza B and H1N1pdm09 also circulated widely. 

     The Influenza Division at CDC antigenically characterized nearly 450 H3N2 viruses collected between Sept 2011 thru Feb 2012 by the hemagglutination inhibition (HI) assay using post infection ferret antisera raised against the current vaccine strain, A/Perth/16/2009, and a panel of reference viruses.  Of the H3N2 viruses tested, the proportion of viruses that demonstrated a > 8 fold reduction in HI titer to A/Perth/16/2009 virus has increased from < 2% to 17% in recent months.  Most viruses tested were well inhibited by antisera raised to recent H3N2 viruses including A/Victoria/361/2011 A small subset of H3N2 viruses were further characterized in the plaque-reduction neutralization assay and results confirmed findings of the HI assay. These data indicate that an increasing proportion of recent viruses are antigenically distinct from current vaccine strain A/Perth/16/2009.  In addition to antigenic characterization, a subset of viruses were genetically characterized by sequencing of the hemagglutinin (HA) and neuraminidase (NA) genes.  Phylogenetic analysis indicates that the H3N2 viruses can be divided by shared amino acid changes into 7 genetic groups.  The most recent viruses fall into group 3 and 6, with group 3 being the dominant and expanding group.  A/Victoria/361/2011 is a representative virus from genetic group 3.

     Similar findings were observed by other WHO Influenza Collaborating Centers located at Tokyo, Melbourne, Beijing, and London.  Thus, during the recent WHO influenza vaccine selection meeting, the H3N2 component of the vaccine for the northern hemisphere 2012-2013 influenza season has been updated; A/Victoria/361/2011 H3N2-like virus has been recommended to replace the current vaccine strain.  
     Virologic surveillance remains critical for detection of antigenic drift among the evolving influenza viruses and to ensure the vaccine strains match circulating viruses as close as possible to provide optimum protection.

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