According to the Public Health Agency of Canada (PHAC), the country is seeing an unusually high number of influenza B cases this season.
Type B flu causes more severe illness in children and has been linked to sudden cardiac death.
So far this season, more than 3,200 cases of flu have been reported across Canada since the end of August.
Of those cases, 1,357 were classified as Type B, with 63 per cent of those patients under the age of 20.
The best protection against influenza is the flu vaccine, which protects against two strains of A and two strains of B.
“Because we have a circulating B strain, the vaccine does tend to work better against flu B, so it’s a good one to get,” said Dr. Jia Hu, medical officer of health for Alberta Health Services in Calgary.
H3N2 and H1N1, two strains of influenza A, are also circulating in Canada this year.
H3N2 is typically associated with more severe illness in older adults, while H1N1 typically impacts younger adults between 20 and 64.
The latest FluWatch surveillance report shows an increase in flu activity through most of Alberta, the B.C. Lower Mainland, southern Ontario and parts of Quebec.
Flu season typically peaks after Christmas, because air travel, large family gatherings or trips to busy shopping malls allow the virus to easily spread.
“The problem with the virus, too, is that you’re most infectious before you have symptoms,” said Dr. Peter Nieman, a Calgary pediatrician.
“So for 24 hours before you know there’s trouble, that’s when you start infecting people.”