An adult male in Ontario has been diagnosed with variant H1N1 influenza. Variant influenza means that the strain normally exists in pigs, but has infected a person. 

This is the first recent identification of a variant influenza strain in a person in Ontario. The media is indicating that the person had exposure to pigs and is currently hospitalized. This variant H1N1 virus is not the same as the pandemic H1N1 strain, so it is currently uncertain whether the seasonal influenza vaccine will provide protection against the variant H1N1 strain.

There has been an increase in variant influenza identified in the US in recent years. Twelve cases were identified from July to December 2011 and over 300 cases have been identified in the US since July 2012. The vast majority of cases in the US have been variant H3N2 (306 cases, 16 hospitalization and 1 death in 2012), although a few cases of variant H1N2 (3 cases since July 2012) and variant H1N1 (2 cases - 1 in 2011 and 1 in 2012) have also been identified in the US. The variant influenza strains identified in the US have been what is called a triple reassortant, in that they contain human, avian and swine genes. The cases identified since 2011 have also contained a new addition, the M gene from the pandemic H1N1 virus. The Center for Disease Control and Prevention (CDC) indicates that it is possible that this gene may make it easier for swine strains to infect people.

The variant influenza cases in the US (which have been mostly variant H3N2) have generally behaved in a manner that is similar to seasonal influenza with similar symptoms and similar complications. Most of the people who have become ill with variant influenza in the US have had direct exposure to pigs (generally at fairs exhibiting pigs), however limited non-sustained transmission from person to person has also been noted.

More information on variant influenza (particularly variant H3N2) can be found on the Centers for Disease Control and Prevention web site.

A fact sheet on variant H1N1 is available from the Ministry of Health and Long Term Care.

Information on influenza vaccine distribution in Middlesex-London will be emailed to you shortly.