The mornings are chilly, the leaves are changing, and the kids are back at school, back sharing their germs with one other — including, eventually, the flu.
Canada is already seeing its first few cases of flu this fall, according to the Public Health Agency of Canada. Experts say that we’re most likely to see a “typical” flu season this year.
Here’s what that means.
When will it start?
Usually, Canada’s flu season starts in the fall and peaks sometime between late December and early February.
When Canadian experts want clues on what our flu season might look like, they often look south, said Alyson Kelvin, an assistant professor at Dalhousie University and an influenza virologist at the Canadian Centre for Vaccinology. Specifically, they look at Australia, which experiences its flu season during our summer (and its winter).
“We can kind of look to see what’s going on there and generally there are trends seen in our later flu season,” she said.
This year, flu season in Australia started very early, with a lot of cases at the beginning of the season, she said, and while it tapered off, still a high number of cases overall.
“It looks like there were these large numbers of cases early, early in the season and everybody of course started worrying and panicking about it because it meant, ‘Oh no it’s going to be a bad year this year and everything else,’” said Dr. Gerald Evans, chair of the Division of Infectious Diseases at Queen’s University.
New data from Australia suggests though that their flu season, while unusual, was shaped by Australia’s unique geography and the same thing probably won’t happen elsewhere, he said. “We have not seen any of that stuff in the other Southern Hemisphere countries. So not in New Zealand, not in Chile and Argentina and not in South Africa, which are the other countries that typically report their flu season data.”
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If we were starting our flu season as early as Australia started theirs, Dr. Michelle Murti, a public health physician with Public Health Ontario, said we would already be seeing lots of cases. But we’re not.
“We’re sort of seeing their usual seasonal levels for this time of year,” she said. “We’re not entering the season in the same way they did. What that means in the end, we don’t know. But I think that’s so far a better sign for us that we’re not entering it at the high levels that they came in at.”
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Both Murti and Evans think that our flu season will likely start at the usual time – beginning to pick up in October, with a peak around the end of December.
How bad will it be?
So far, signs are pointing to Canada’s flu season not being especially rough this year.
Looking at Australia, Kelvin said, while they had a lot of cases of flu, relatively few people got seriously sick from it.
“The good news is that even though they had a higher number of reported cases, that when we actually measure influenza severity, which is the number of hospitalizations and deaths, their rates were quite low,” she said.
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Evans expects a normal number of people to be infected (in Canada this is about 40,000 confirmed cases on average over the last five years), with a normal number of hospitalizations and deaths.
There could be one complication though: this year, the predominant flu strain in Australia was of the H3N2 type, which often causes a more severe illness, Evans said.
“Typically H1N1 seasons are a little bit milder because more of the senior population have some immunity to H1N1,” Murti said. “So we typically see less cases in an H1N1 year compared to an H3N2 year.”
How good a match will the flu vaccine be?
The flu shot typically protects against H1N1 strains, H3N2 strains, as well as two types of Influenza B, Kelvin said. Every year, the WHO meets to decide what strains should be targeted by the vaccine — picking those that are most likely to be spreading during the upcoming flu season.
“You can think of the vaccine as almost a multivitamin that has these four different components or material to protect you from these four different viruses,” she said. “And what we want to do is actually match what’s circulating in people with our yearly influenza formulation.”
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Unfortunately, it’s harder to guess the H3N2 strain correctly, Murti said. It frequently mutates, so that the vaccine becomes less effective. It can also mutate in the lab, while drug manufacturers are growing the vaccine, so that what ends up in your flu shot might no longer be quite what was in the environment, she said.
So if H3N2 predominates this year, Evans said, there may be a bit of a “mismatch” between what the vaccine is protecting against and what we encounter.
How should you protect yourself?
With that said, he still thinks you should get the flu shot. “The flu shot is useful for everyone in terms of reducing either the chance of getting influenza, and also if you do get it, it should reduce the severity of it by giving some primed immunity to the virus itself.”
“As soon as the vaccine becomes available, that’s our number one thing to say, that people – particularly those who are at high risk for influenza – should be getting the flu shot,” Murti said.
That includes people over 65, children under five, pregnant women and people with underlying health conditions like heart disease, respiratory disease, diabetes and obesity.
If you’re in one of these high-risk groups that could potentially have a more severe reaction to the flu, she said, you might even want to consider consulting with your physician before flu season really starts, to figure out a plan of action should you get sick. This could include things like having easy access to a prescription for antiviral therapy.
Aside from the flu shot, you should also wash your hands frequently, cough into your elbow or sleeve instead of your hand, and stay home if you’re feeling ill, she said.
If you’re sick with a respiratory illness and you’re feeling short of breath, have a persistently high fever, or have an illness that goes away after a few days but then comes back hard, Evans says these are all signs that you should visit a doctor.
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