Distributed by e-mail December 10, 2013

The latest Influenza Surveillance Report was posted on the Health Unit’s web site today. The current level of activity indicates the arrival of influenza in the community. From November 28 to December 8, five cases of laboratory-confirmed influenza A were reported to the Health Unit bringing the total this influenza season to seven.

Three samples from Middlesex-London have been typed as influenza A(H1N1)pdm09; this is the same strain that circulated during the 2009 pandemic. Of the influenza A strains that have been subtyped across Canada, 77% are the 2009 pandemic strain.

So far, there appears to be a very good match between circulating strains and the vaccine. The H1N1 Pandemic strain (that has been identified in three of Middlesex-London’s laboratory-confirmed cases and 77% of the influenza A strains that have been subtyped across Canada) is in the vaccine.

This week’s Influenza Surveillance Report states the following:

"In Canada, 57 influenza viruses (41 influenza A and 16 influenza B) have been antigenically characterized since the beginning of the current season. Of the 57 influenza viruses, 91.2% matched the components of the 2013/2014 influenza vaccine. The components of the 2013/2014 influenza vaccine are: A/California/7/2009 (H1N1) pdm09-like virus, A/Victoria/361/2011b (H3N2) virus, and a B/Massachusetts/2/2012-like virus. The latest FluWatch report can be accessed through the following link: http://www.phac-aspc.gc.ca/fluwatch/ ."

It is definitely not too late for unvaccinated patients to receive the vaccine as influenza season can last until April.

In addition to influenza A, some Respiratory Syncytial Virus is also being noted in Ontario, although rhinovirus remains the predominant circulating respiratory virus. Additional information on respiratory infections in Ontario can be found on the Public Health Ontario web site.