The influenza season in Canada could be shaping up to be a potentially nasty one, with a mixed bag of viruses already circulating in much of the country, say infectious diseases experts.
There are also concerns that this year’s flu shot may not be all that effective in preventing the respiratory illness.
“There’s all kinds of speculation going on because of the experience in the Southern Hemisphere,” said Dr. Danuta Skowronski of the B.C. Centre for Disease Control, referring in particular to Australia.
“They had quite a substantial epidemic due to H3N2, so there’s a lot of speculation that that’s foreboding a severe season for us also,” she said from Vancouver.
H3N2 is a subtype of influenza A, viruses which tend to cause more severe disease in some segments of the population, specifically the elderly and young children.
Australia flu deaths double from last year
At the end of its flu season in mid-August, Australia had more than 93,000 laboratory-confirmed cases — almost 2.5 times the number of infections and double the number of hospitalizations and deaths compared to the previous year, the country’s disease surveillance system reported.
“But we cannot say we will go on to experience the kind of severe season Australia had, in part because we ourselves had a fairly severe epidemic due to H3N2 in 2016-17,” Skowronski said. “And that may dampen down the contribution of H3N2 this season, which would be a good thing.”
However, Australia also experienced significant cases of influenza B, said Skowronski, and parts of Canada appear to be mimicking that pattern in the early months of the Northern hemisphere’s flu season.
In B.C., for instance, low levels of H3N2 infection have been confirmed since the beginning of the season in late August, but a strain known as B/Yamagata has also been found circulating within the population.
“And this is very early. We’re having about five times the amount of influenza B pickup during the autumn period in British Columbia than we typically have,” she said. “We don’t normally see this kind of influenza B uptick until February, so this is quite unusual.
“If this persists, there could be kind of a double-barrelled threat with B/Yamagata and influenza A/H3N2.”
8 deaths in Canada
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