In 2009, Ontario was hit with a strain of swine flu commonly known as H1N1. It was a pandemic strain claimed the lives of many and triggered widespread vaccinations.
And now, Ontario health officials have confirmed a similar strain is back, with thousands of cases being reported across the province since September.
According to Dr. Bryna Warshawsky, a medical director with Public Health Ontario, the H1N1 strain that is circulating is very similar to what began in 2009.
When it first appeared 10-years-ago, a majority of people, particularly younger children and adults, had not experienced it before, resulting in many people getting sick not just in Ontario and Canada, but around the world.
Older adults were more protected from the strain as it was similar to another strain that had circulated many years prior that they may have been exposed to when they were younger.
“Since 2009, the H1N1 strain has reappeared as the dominant strain circulating during several flu seasons (2013-2014 and 2015-2016). In addition, we have vaccinated against this strain of H1N1 in 2009 and every year since,” says Dr. Warshawsky.
Because this strain has circulated a number of times since 2009 and we continue to get vaccinated, people have more immunity now, so few fewer people are getting ill.
Ontario is seeing cases of both H1N1 and H3N2
So far this year, Dr. Warshawsky says there are more H1N1 cases being reported across the country. But here in Ontario, there is also a low-level of H3N2 circulating, which is another type of influenza A.
From September 1 to December 29, 2018, Dr. Warshawsky says there have been 1,767 laboratory-confirmed cases of influenza reported in Ontario.
“This only represents a fraction of the people who are infected with influenza, as many people with influenza are not tested to see exactly what is causing their symptoms,” says Dr. Warshawsky.
As for where cases are specifically appearing in the province, Dr. Warshawsky says influenza activity is wide-spread with “some variability in the rates of laboratory-confirmed infections.”
Common symptoms include fever, chills, cough, sore throat, body aches and fatigue. However, while many symptoms of a cold may appear similar to influenza, influenza symptoms tend to be more severe.
“As an example, people with influenza can feel extreme fatigue with little energy to get out of bed,” says Dr. Warshawsky.
“Influenza tends to be more serious than the average cold, as it can cause complications that result in hospitalizations and deaths, such as pneumonia, and worsening of underlying medical conditions such as heart disease or lung disease. Influenza infections have also been linked to heart attacks.”
As we dive into winter, the best way to ensure you’re protected is to get the influenza shot if you haven’t already.
“Each year’s influenza vaccine contains two strains of influenza A – one H1N1 strain and one H3N2 strain, as well as one or two influenza B strains,” says Dr. Warshawsky.
Influenza B tends to occur later in the influenza season, often when influenza A activity is decreasing.
Dr. Warshawsky says this year’s influenza vaccine contains the H1N1 strain, which in past years has been shown to be fairly effective in protecting against the H1N1 strains that have circulated in those years.
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