For more than two years, while Canadians were experiencing a train in an amusement park from COVID-19 infections, the flu seemed to have receded.
The family of viruses that cause the flu has hardly spread across the country until the recent belated return of influenza A caught the attention of scientists.
In March – after restrictions on COVID-19 were lifted and more people began to mix – positive tests for influenza A viruses began to rise in Canada. By the end of April, show federal data almost seven percent percentage of test positive, close to the average for this time of year and largely caused by a jump in Quebec.
This unusually late flu season may offer clues as to how COVID and influenza will interact in the coming years, with one theory suggesting that these two warring viruses could withdraw and fade away – but it’s hard to predict exactly how it seems so.
“It will be interesting to see what happens as COVID becomes less dominant if the flu starts to compete with it and they have a tug of war over the next few years,” said Dr Sumon Chakrabarti, an infectious disease specialist. Diseases from Trillium Health Partners in Mississauga, Ont.
The flu usually increases in the winter
In a typical flu year, the cases first rise in the fall, increase in the winter and decrease in the spring, with sporadic infections throughout the rest of the year – with influenza A viruses circulating before influenza B.
The disappearance of viruses during the pandemic may be due in part to changes in behavior for most of the last two years, as COVID-19 has grown unpredictably, option after option.
“We have been able to successfully suppress the circulation of influenza with our other public measures related to COVID-19,” said Dr. Danuta Skowronski, head of epidemiology for influenza and emerging respiratory pathogens at the BC Centers for Disease Control.
The removal of restrictions, combined with an increase in global and domestic travel, may have played a role in the return of influenza in recent months, said Dr. Isaac Bogoch, an infectious disease specialist at the University Health Network in Toronto.
An inadequate flu vaccine this season may be another factor behind this unusual jump, as reported by US health authoritiesor just a weakening immunity from shots fired in the fall, according to Skovronsky.
But some avid observers of COVID-19 say the virus that causes it, SARS-CoV-2, may also have helped keep the flu at bay.
A sign indicating the expected waiting time at Humber River Hospital was displayed in her emergency room in Toronto on April 26. The hospital is facing a larger number of patients and an increase in influenza cases. (Alex Lupul / CBC)
Viral Intervention
There was once speculation that COVID-19 and the flu could create what some have called “twindemia”, both types of infections affected the parties simultaneously, but these fears did not materialize.
Instead, some medical experts say there may be some level of “viral intervention” in which a virus such as COVID-19 pushes other pathogens to the population level over a period of time.
“There’s some kind of interesting viral suppression and competition going on here,” said Chakrabarti, who suggested that COVID and the flu could weaken and infiltrate the circulation.
During the pandemic, he explained, widespread COVID-19 infections may have kept people’s immune systems on high alert, giving SARS-CoV-2 a long-term advantage over the flu.
Influenza A cases began to rise in Canada unusually late this year, after public health restrictions were lifted and more Canadians began mingling and traveling. (Alex Lupul / CBC)
“There have been outbreaks of the flu this year, mostly in the pockets of the United States, but it was clearly not an ordinary flu season and the flu was clearly suppressed,” Bogoch reiterated.
“People are talking about influenza and COVID now, and I wouldn’t ignore anything. I think the short answer is that you can’t be too sure how it will develop next year or more. “
On the other hand, viral scientist Alison Kelvin of the University of Saskatchewan’s Organization for Vaccines and Infectious Diseases said the sudden return of the flu may actually be linked to the bluntness of millions of Canadians in the fifth and sixth waves of COVID-19. Covid19 infection.
“The circulation of SARS-CoV-2 – particularly Omicron – may have left people slightly immunocompromised,” she said.
“Once the virus enters and infects people, their immune systems are weaker, leaving the possibility of influenza A infecting people in the weeks after their initial Omicron infection.
WATCH The Canadians called for boosters during the 6th wave:
Canadians call for booster vaccines against COVID-19 to blunt 6th wave
All indications are that Canada is going through the sixth pandemic wave, confirms Dr. Teresa Tam. Her message to Canadians: wear a mask and get stronger if you meet the conditions. 02:00
A different model of influenza is possible
Several experts who spoke to CBC News agreed that there could be unexpected changes in the flu season based on how the virus behind COVID-19 works in the future.
“Will the cases of SARS-CoV-2 and COVID-19 become more seasonal?” If so, we can see a different pattern of flu, “Kelvin said.
In the short term – more reassuringly – both viruses are expected to disappear when the weather warms up before returning, at some point, in the fall.
This lull is a time when health systems and governments need to start planning for an uncertain future, according to Dr. Leon Rivlin, head of emergency medicine at Humber River Hospital.
Dr. Leon Rivlin, head of emergency medicine at Humber River Hospital, in the emergency department in late April. It is preparing to increase the number of COVID-19 cases. (Alex Lupul / CBC)
Right now, as flu cases are on the rise, hospitals are still facing a shortage of COVID-19-related staff, he said. Seven doctors from his team called patients on suspicion of SARS-CoV-2 infections just last weekend.
“We will have this rise again,” he warned. “And again, we will be focused on human resources.”
The coming months can be crucial to ensure that Canadians continue to receive vaccinations that offer protection against serious diseases, while politicians ensure that there is enough space and staff to deal with patients who really care. seriously ill with COVID-19 or influenza.
“There will be both short-term and long-term solutions,” Chakrabarti said. “Ultimately, we need some way to absorb any sudden outbreaks of infections that occur.”
Add Comment