The predominant strain that is circulating is a “severe one,” according to Dr. Isaac Bogoch, an infectious disease specialist at University Health Network in Toronto. It’s also possible the flu vaccine may have limited effectiveness against it, he added.
“It could be a severe year. There is data coming out of Australia, which also has this strain, that says part of the vaccine may have not been as effective at protecting against the flu as we would want,” he said.
“And what happens in Australia’s flu season usually migrates to us.”
What strains are making people sick this year?
There are two primary flu strains that are making people sick.
The dominant influenza A strain is H3N2 and it is the “big” one to worry about, Bogoch said.
“The predominant H3N2 strain has a history that shows it causes more cases of the flu and more deaths,” he said.
Influenza B is the other strain — but it’s not as nasty. This year’s B strain, known as B/Yamagata, began circulating in the fall, much earlier than usual and is “substantially greater this season” compared to others, according to the Canadian Public Health Agency.
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Although it’s still too early to know how bad this flu season could get, Bogoch said there is a small indication that there could be more cases than last year.
To date, there have been 34 deaths in Canada related to influenza.
When does flu season peak?
We are currently in the middle of the influenza season. Bogoch said it should peak in the middle of January and then decline in late February and early March.
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Is this year’s flu shot working?
Each year, the flu vaccine contains protection against two strains of influenza A and one strain of influenza B.
It’s still too early to know how effective the vaccine will be in Canada, but there is an indication it could be weak.
Bogoch said this is because regions in the Southern Hemisphere, such as Australia and Hong Kong, only saw around 10 per cent effectiveness against H3N2.
What happens in the Southern Hemisphere usually lays the groundwork for predicting which viruses are out there by the time they make their way north.
“It’s not perfect, but it’s the best we got,” he said.
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Why you should still get the flu shot
Bogoch said there are multiple strains of the flu going around. So if the vaccine does not work on one strain, it could work on another.
And even if the vaccine is a mismatch, those who get the flu shot typically end up with milder symptoms if they get the flu. It also helps provide protection for your family and co-workers, especially if you have young kids or elderly people living with you.
It’s still not too late to get the flu shot as there are around eight to 10 weeks left in the season.
How does the flu work?
The flu is a respiratory illness caused by the influenza virus and is not the same as a cold (which is caused by a different virus).
When the influenza virus gets into the body it heads into the respiratory tract, binds to the surface of cells and starts replicating. The virus then takes over the function of the cell.
This causes the respiratory system to swell and become inflamed. The virus then enters the bloodstream and the first symptoms begin to appear, such as coughing, fever, body aches and sneezing. The replication process continues for up to several days until the body’s immune system fights off the virus.
How to protect yourself
There are three main ways to protect yourself and others from getting the flu, according to Bogoch.
- Get the flu shot
- Wash your hands
- Stay home if you’re sick
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