This flu season nothing to sneeze at

Concerns that this year’s flu shot may not be all that effective

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 BC 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.

RELATED: Flu season is here

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.”

In its weekly FluWatch report, the Public Health Agency of Canada says the annual sneezing-coughing season began early this year — especially with illness due to influenza B — and the percentage of laboratory-positive tests for flu is higher at this point on the calendar compared with previous seasons.

As of Nov. 25, almost 2,100 lab-confirmed cases had been detected in various parts of the country, of which 84 per cent were influenza A. Those infections resulted in 371 hospitalizations, including 21 ICU admissions, and eight deaths, the report says.

Dr. Allison McGeer, director of infection control at Mount Sinai Hospital in Toronto, said lab testing in Ontario is turning up ”quite a lot of B isolates, nearly as many Bs as H3N2.”

But she said it’s too early to predict what strain will predominate or how severe the season will be.

“This prediction ahead of time is a mug’s game, but I think it’s probably not going to be an H1N1 season,” McGeer said. ”But whether it’s going to be a B or H3N2 or mixed is still open.”

Added to that uncertainty is the question of how effective this season’s vaccine may be in preventing people from getting the flu.

This year’s shot is the same as the one used in 2016-17, containing components for three major strains: A/H1N1, A/H3N2 and B/Victoria, based on a recommendation by the World Health Organization made in February.

However, the shot does not provide exact matches for the H3N2 and the B strains now circulating, said Skowronski.

In the case of H3N2, the vaccine component has been genetically altered somewhat as a result of the manufacturing process, which involves growing vast quantities of the virus in eggs.

And the B strain circulating isn’t a Victoria lineage as predicted by the WHO, but a Yamagata known as B/Phuket.

Last year in Canada and the U.S., the vaccine was found to be only 35 per cent effective in preventing cases of H3N2 influenza, she said. And in Australia, which used the identical vaccine as Canada’s this past season, its effectiveness against H3N2 infection was far less – only about 10 per cent.

“So given that, particularly for the H3N2 component, the vaccine effectiveness we’re anticipating will be low,” predicted Skowronski.

RELATED: Flu vaccine effectiveness called ‘decent’

Despite those misgivings, she encourages the elderly and those with underlying heart and lung conditions or with suppressed immune systems, who are vulnerable to influenza and its complications, to get their shot to obtain ”all the protection you can get.”

Health-care workers and people whose close contacts have underlying medical conditions have additional impetus to get inoculated against the flu, she said.

“But for others, healthy young adults with no comorbidity and no close contacts with such conditions, it’s a personal choice. And this isn’t the season to be thumping the pulpit over that.”

Still, McGeer said there’s good evidence accumulated over time that getting the flu shot every year “is a safer and healthier thing to do for myself and better for my patients and my family.”

And while it may not work well against H3N2, she said it’s worth getting the shot for protection against infection with H1N1 and even the B strain (the B/Victoria components may offer cross-protection against B/Yamagata).

“Yeah, it’s not a great vaccine, but it’s a lot better than nothing.”

The Canadian Press

Like us on Facebook and follow us on Twitter.

Just Posted

Kootenay National Park No Stopping Zone in effect

No stopping and area closures during bear

Canal Flats Council briefs

Budgets, zoning, grants and more

Minimum wage goes up again

Increase goes in effect June 1st to $15.20

RCMP Report

Some of the more interesting callouts this past week for Columbia Valley RCMP

Recreation plans, Segways and a take-out restaurant in Radium

Eclectic collection of topics discussed at last Radium Council meeting

UPDATE: B.C. pilot killed in Honduras plane crash

The crash happened in the Roatan Islands area, according to officials

Raptors beat Bucks 118-112 in 2OT thriller

Leonard has 36 points as Toronto cuts Milwaukee’s series lead to 2-1

‘Teams that win are tight’: B.C. Lions search for chemistry at training camp

The Lions added more than 50 new faces over the off-season, from coaching staff to key players

Rescue crews suspend search for Okanagan kayaker missing for three days

71-year-old Zygmunt Janiewicz was reported missing Friday

B.C. VIEWS: Reality of our plastic recycling routine exposed

Turns out dear old China wasn’t doing such a great job

Carbon dioxide at highest levels for over 2.5 million years, expert warns of 100 years of disruption

CO2 levels rising rapidly, now higher than at any point in humanity’s history

B.C. ferry stops to let black bear swim past near Nanaimo

Queen of Oak Bay brakes for wildlife in Nanaimo’s Departure Bay

Mother dead, child in critical condition after carbon monoxide poisoning at Shuswap campground

The woman was found unresponsive insider her tent and the youth was taken via air ambulance to hospital

Canada’s parole officers say correctional system has reached breaking point

About half of Canada’s federal parole officers work inside penitentiaries and correctional institutions

Most Read