There were almost no flu cases in Canada last year. Will that make this year’s season more deadly?

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Canada’s still fragile medical system prepares for flu season that some experts fear after COVID-19 measures last year inadvertently suppressed the virus, reducing natural immunity.

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Flu vaccine shipments have already started nationwide, and Ontario says it is preparing for its largest flu vaccine campaign in provincial history.

Last winter, public measures designed to stop the spread of the coronavirus had the unintended consequence of the flu being almost non-existent. But the easing of restrictions and cooler weather suggest a return to indoor spaces, with some warning about the possibility of a rebound season, in which the flu virus has gained a foothold thanks to the lack of natural immunity generated last year.


The head of the Centers for Disease Control has warned that the US could be at a risk for severe weather, while Canada’s Public Health Agency said in a statement it was prepared for a possible resurgence.

“Last year, because of the lockdown, public health, distance, masking, hand washing etc., there was actually very little influenza,” said Dr Anna Banerjee, an infectious disease specialist at the University of Toronto. “When you haven’t had influenza for a while, it’s usually more severe than when it comes back.

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“I think it will probably be a very deadly flu year.”

While a spike in the flu will send patients to intensive care units already overwhelmed with COVID patients, experts point out that the solution here is a familiar one: vaccination.

Unlike last year, shots in Ontario will be available to people at high risk from mid-October, and will open to the general population in November.

One of the reasons the flu is so clever is how quickly it mutates—in COVID-speak, there are thousands of types circulating at any one time. When people are infected with the flu, and when they get the flu shot, which is designed to ward off three or four strains, people build up immunity to different strains.

You get a new shot every year, not because the previous one got worse, but because the flu usually has developed.

As Scott Simpson, a pharmacy professor at the University of Alberta, puts it: “The way the influenza virus works is it changes its coat. Instead of wearing a blue, down-filled jacket like a year, it rains green. will be reducing.”

Like every year, these shots have been in development since February, when the World Health Organization made its predictions for which strains would be effective in the Northern Hemisphere this season, with many vaccine makers starting to drink this year’s shots.

Several companies began making flu shots, sometimes using slightly different techniques or doses, but targeting the same virus as determined by the WHO.

Bruce Seit, director of medical affairs at Sanofi Pasteur, one of the companies that manufactures large quantities of flu vaccines for the Canadian market, says, “Influenza is probably one of the most complex and dynamic viruses we face in public health. are.”

It’s a constant arms race, he says. Not only must scientists predict which strains will be dominant, but there may be different versions in different locations, or even some genetic variation within seasons.

It’s also just one big undertaking – much of Sanofi starts with millions of fertilized chicken eggs, which are killed, sterilized and made in varying doses that are used to make the virus in large quantities. which, hopefully, will teach your body how to fight the flu.

Seet says it’s not clear whether last year’s short flu season will affect this year’s shot. On one hand, less flu last year means less data from which to make a new shot, he says. But fewer flus could mean that entire families of flu viruses went extinct.

As always, the biggest question mark of the flu is what Seit calls its superpower: It mutates and grows rapidly.

“It’s a moving target,” Seit says. “But at the end of the day, it’s like shooting at 1,000 different targets.”

Experts say the shots will be especially important this year, as some worry the lack of natural immunity.

A preprint article published in August by a group of US researchers – which has not yet been reviewed by other scientists – predicts a “big compensatory influenza season” this year.

As stated in the study, “During the season with low influenza activity in 2020-21, populations missed the opportunity to establish or enhance their immunity to future influenza seasons.”

in a releaseMark Roberts, director of the Public Health Dynamics Laboratory at the University of Pittsburgh, said the lifting of COVID-19 containment measures resulted in “a horrific resurgence of other respiratory viruses, which is not good for the coming flu season.”

As you progress, the risk increases. If the flu remains low for several seasons, the number of susceptible people will continue to grow, leading to a major outbreak.

But the modeling also points to the importance of vaccination. Hospitalization will remain the same if there is an improvement of up to 50 percent in either vaccine introduction or efficacy (or if there is only a 25 percent improvement in each).

The stakes here are clear – with intensive care units across the country currently under siege from COVID, a resurgence of the other disease could overwhelm them.

The authors acknowledge the study’s own limitations – in particular, it is difficult to tell when natural or vaccine-induced will end, or how much the virus will change.

Simpson says it’s too soon to know what flu season will be like, though he’s optimistic that masking and social distancing will have the same effect as last year, when flu season ended.

While there was less information to draw from last year, he points out that there was still enough information for the WHO to recommend a new cocktail of strains of the virus – this year’s flu shot includes a strain that was similar to that of 2013. Has been around, and a new one that was only recognized last year.

There is some debate, Simpson says, about how prepared you are usually if you get the shot each year, with some research showing that having a “nakshatra of antibodies” from various flu shots in your system can help protect your body. There may be a fighting chance in identifying new strains.

but According to Health CanadaThe virus is estimated to affect between five and 10 percent of adults and 20 to 30 percent of children worldwide each year. Together, the flu and pneumonia are among the 10 leading causes of death.

Over the past 10 years, an average of 30,000 laboratory-confirmed cases of flu were reported in a national surveillance program called FluWatch.

Pam Tomasevic begins her search every year in early October — she begins calling doctors’ offices and pharmacies in an attempt to find a flu shot.

Going into the second pandemic winter, Tomasewicz, a senior living in Mississauga, wanted to make sure she was protected from both viruses, but says there isn’t much information available yet.

“It’s frustrating when everyone is left to figure it out for themselves instead of having some standard information available to everyone,” she said.

Especially now that things are a little more open,” she says. “I want to be safe on all fronts: COVID and flu.”

Experts hope that after a year of hearing about vaccines, more people have heeded the call for vaccinations. Simpson sees hope in the fact that people are more aware than ever about vaccine technology.

“I think that’s a good thing because, people are becoming more aware that first of all, they are susceptible or if they develop an infection, these infections can be quite serious.”

Seat points out that while seniors get a higher number of flu shots, vaccination rates among adults are often only 20 to 30 percent. He says the worst thing we can do is underestimate the flu. Often characterized as snuff, it has great potential for global spread.

“If there are still many people who do not get vaccinated against influenza, that means there are more chances of transmission and variation,” he says.

“Having a large unrelated population sets up the conditions for viruses to do what they do. To be opportunistic.”

Correction – October 10, 2021: This article was edited to correct that millions of fertilized chicken eggs are used, not thousands as mentioned in the previous version.

Alex Boyd is a Calgary-based reporter for Star. Follow him on Twitter: @alex_n_boyd

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