This year’s flu season, predicted to be relatively mild, is defying expectations.
According to surveillance data released by the Public Health Agency of Canada on Friday, there have been 13,796 laboratory-confirmed influenza cases across Canada this season, up until December 29, 2018.
At this point a year ago, there were 11,275 confirmed cases. Last year’s season was thought to have been particularly rough.
“It’s a substantial season,” said Dr. Scott Halperin, director of the Canadian Center for Vaccinology at Dalhousie University.
“Last year was a relatively busy season for flu and this year looks like another busy season.”
So far, provinces have reported 1,046 hospitalizations related to influenza and 24 deaths. Most confirmed flu cases and hospitalizations have been of people under the age of 65.
“About two-thirds of the cases have been in people who typically think that they don’t get sick from influenza, that’s not the case with this virus. This virus does hit young, healthy adults.”
There were more flu-related deaths a year ago: 34 by the end of December.
This year’s flu season started earlier than usual, according to reports from the Public Health Agency of Canada. Almost all flu cases have been influenza A, and of those they were able to test in detail, most were the H1N1 virus subtype.
That virus is similar to the one that caused the flu pandemic in 2009, said Halperin, but hasn’t been predominant since then — meaning that many people likely don’t have immunity to it anymore.
The predominant flu strain could also change later in the season, he said.
“Many flu seasons have a biphasic appearance. So you get A circulating and then towards the end you start seeing some B activity,” he said. “Typically in Canada, we see B seasons tend to be towards the end of the season, so later in the winter.”
And although we’re now nearing the peak of flu season, Halperin still recommends getting the flu shot if you haven’t yet. There’s still a lot of flu season left.
“Those people, if they go out and get the vaccine now, in 10 days to two weeks they’re going to have some protection and that may protect them against a substantial part of the season.”
The flu shot is likely to help a lot too this year, he said, as the vaccine is usually good at matching H1N1 strains. And it can help protect against a possible late-season influenza B outbreak. “The vaccine does contain the B virus as well. So it can protect them against that later bump if we do have it this year.”