What's a syndemic and do I need to worry about it amid COVID & flu season? How Canadians can stay safe

Cases of COVID, the flu and RSV are rising south of the border, but Canadians aren't in the clear.

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Are Canadians in store for a "syndemic" this winter? Here's what you should know. (Getty Images)

Public health experts have warned the United States is a "sitting duck" in the face of a "syndemic" winter as surges of flu, RSV and other pathogens combine with high levels of COVID-19 infections.

Jay Weiland, a top COVID forecaster, told Fortune in late 2023 there is a "reasonable chance" this winter's COVID wave will surpass that of 2022, when a "tripledemic" of pathogens pushed children's hospitals beyond capacity south of the border.

U.S. COVID-19 hospital admissions have been rising since November, according to The Hill, and flu activity is "elevated." Meanwhile, vaccine uptake for the flu in December was down by 8 million people compared to the same period in 2022, and only about a fifth of U.S. residents got the new COVID-19 shot, polls say.

According to data from the Centers for Disease Control and Prevention, outpatient visits for respiratory illnesses are unusually high for this time of year — and rates of hospitalization from RSV and flu continue to rise.

Canada saw more than 10,000 cases of COVID in the last week of 2023, while "activity of flu is highest and increasing," at more than 7,000 cases that week. But should Canadians be worried about the effects of a syndemic this season?

Read on for everything you should know.

What is a syndemic, and how is it different from a tripledemic?

"A season that's like last year would be reasonable to predict — which was much more intense than what we're used to experiencing in pre-pandemic years," Dr. Matthew Miller, director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University, recently told Yahoo Canada.

By this time last year, there were significantly higher numbers of COVID, RSV and flu viruses across Canada, particularly among children.

All three viruses peaked early last year, which led to the term "tripledemic" being coined, leaving several emergency rooms across the country overwhelmed. The significantly high number of patients infected with these respiratory viruses caused major surgeries to be cancelled and supplies of children's pain medication to dip dangerously low.

Last year, there were significantly higher COVID, RSV and flu cases across Canada, especially amongst children. (Photo via Getty Images)
Last year, there were significantly higher COVID, RSV and flu cases across Canada, especially amongst children. (Photo via Getty Images)

So what is a syndemic?

"A syndemic is a more general term that conveys the same thing but with more breadth," Miller explained. "In addition to RSV, flu and COVID, a syndemic conveys the synchronicity amongst a wide range of pathogens that circulate together causing seasonal epidemics.

"Viruses that cause the common cold and mycobacterial infections we've been hearing about in China and Europe may also be cause for concern this year. But flu, COVID and RSV remain of highest concern because they cause more severe infection, especially in high risk populations."

Should Canadians be worried about a syndemic flu season?

The Public Health Agency of Canada's latest FluWatch report shows COVID rates have risen slightly since the beginning of the month — but trends vary significantly by region. Rates of RSV and influenza are also increasing, but are "within expected levels for this time of year."

Dr. Vinita Dubey, Toronto Public Health's associate medical officer of health, said at a virtual Ontario Medical Association conference a "triple threat" of respiratory viruses is expected to hit Canadians again this winter

"We are expecting to see a heavy respiratory virus season, particularly with those three, RSV, influenza and COVID, among other viruses spread around [the flu season]," she said, referring to a possible syndemic.

Masking in crowded, indoor spaces is an important way to stay healthy during peak circulation of these viruses. (Photo via Getty Images)
Masking in crowded, indoor spaces is an important way to stay healthy during peak circulation of these viruses. (Photo via Getty Images)

How can you protect yourself from COVID, flu, RSV and other seasonal illnesses?

According to Miller, masking is especially important during the winter months when there's peak circulation of these viruses and you're more likely to be indoors in a space that's crowded — like holiday shopping and travelling.

"Putting on a mask is such an easy and effective thing to do with no risks associated with it," he said.

Vaccination also remains one of the most effective ways to protect yourself and your family from infection.

"We now have updated SARS-Cov-2 boosters, seasonal flu vaccines, and what's exciting is in Canada we have a brand new RSV vaccine available this season to older adults," he explained.

"That's really low hanging fruit in terms of an easy way for people to protect themselves, especially if they belong to a high risk population."

New strains of COVID-19 continue popping up quickly and most vaccines only provide protection for roughly three months post vaccination.

Miller said staying up to date on your vaccines now can help people over the holiday season, "providing protection during a time when people are disproportionately gathering indoors in a more crowded setting." He added everyone who is eligible should be getting vaccinated — if not for yourself, then to protect those around you.

"It's imperative that we preserve the capacity of the health-care system given that we know now that we don't have a lot of ability to deal with surges," he cautioned.

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