2008/2009 Influenza

If you got a flu shot this year in the United States you got vaccinated against the following three strains:

• A/Brisbane/59/2007(H1N1)-like virus
• A/Brisbane/10/2007 (H3N2)-like virus
• B/Florida/4/2006-like virus

Currently the H1N1 strain is the most prevalent in the US and so the vaccine should give good protection. However the current strain of H1N1 is increasingly resistant to Oseltamivir, sold in the US as Tamiflu. The most recent data suggests 96.5% of H1N1 samples tested were resistant causing the CDC to issue a health advisory notice.

Recommendations are already being made for the 2009/2010 vaccine:

WHO has recommended vaccine strains for the 2009-10 Northern Hemisphere trivalent influenza vaccine, and FDA has made the same recommendations for the U.S. influenza vaccine. Both agencies recommend that the vaccine contain A/Brisbane/59/2007-like (H1N1), A/Brisbane/10/2007-like (H3N2), and B/Brisbane/60/2008-like (B/Victoria lineage) viruses. Only the influenza B component has been changed from the 2008-09 vaccine formulation. This recommendation was based on surveillance data related to epidemiology and antigenic characteristics, serological responses to 2008-09 vaccines, and the availability of candidate strains and reagents.