White Coat, Black Art·The Dose

Viruses limited by COVID-19 restrictions are coming back strong this fall, experts say

With public health measures easing in many places and more people travelling, a variety of non-COVID respiratory viruses are rearing their heads again this fall, experts say.

Tips for what to watch for and how to stay healthy

A variety of non-COVID-19 respiratory viruses, including the cause of the common cold, are circulating more widely this fall, experts say. (Credit: iStock/Getty Images)
Viruses dampened by Covid-19 restrictions last year are coming back strong this fall. If you take a Covid test and it's negative, how can you figure out what virus you might have?

If you've felt sick at any point over the past year and a half, COVID-19 was likely your main concern. But with public health measures easing in many places and more people travelling, a variety of other respiratory viruses are reappearing this fall. 

Dr. Zain Chagla, an infectious disease physician and associate professor at McMaster University in Hamilton, said common respiratory viruses such as enterovirus and rhinovirus — which causes the common cold — saw low rates of transmission last winter due to physical distancing and mask wearing. But they began circulating more widely over the summer. 

"We've now completely altered the seasonality of these and have reintroduced them back in the population," Chagla told Brian Goldman, host of White Coat, Black Art and The Dose. "We're seeing very atypical patterns of disease that we've never seen before."

All of this means keeping an eye out for the return of some old, familiar illnesses.

Common cold, parainfluenza and influenza are back

With children back in school, expect even more enterovirus and rhinovirus in the coming weeks, said Chagla.

Parainfluenza, which he described as "a cousin of influenza," showed up again in parts of Canada in July and August. Parainfluenza is caused by a different virus, but the symptoms are similar to influenza, including fever, cough and sore throat.

As for influenza itself, Chagla said it's difficult to predict what kind of flu season Canada is in for. 

Dr. Zain Chagla, an infectious disease physician and associate professor at McMaster University, says with children back in school we'll see more cases of rhinovirus and enterovirus, which were less prevalent earlier in the COVID-19 pandemic. (St. Joseph's Healthcare)

Last year's flu season was almost non-existent due to COVID-19 measures. Canada usually gets a preview of the upcoming flu season by watching Australia and New Zealand during their winter. But those countries saw low flu activity again this year, likely as a result of COVID-19 lockdowns. 

Places such as Asia, sub-Saharan Africa and South America have seen more influenza transmission over the past few months, said Chagla, which means Canada will likely see more influenza this year, too, though maybe not at pre-pandemic levels.

RSV a concern for young children

RSV, or respiratory syncytial virus, is another virus making a comeback, said Chagla.

"Certainly, this is one where parents do need to be on the watch," he said, as it can lead to hospitalization for young children. 

Wheezing, lethargy, persistent cough, or difficulty breathing are all signs that medical treatment is needed. 

Pascal Lavoie, a pediatrician and clinician scientist at the B.C. Children's Hospital Research Institute in Vancouver, said RSV is one of the most serious viruses for vulnerable infants. 

He said cases are on the rise in Eastern Canada and the United States. Lack of exposure to the virus over the past year is a concern, he said.

"People often ask, 'Is our immune system weaker?' It's not weaker, it's just not as prepared to fight those viruses," he said. "Based on that, we anticipate it's going to be a tough winter." 

Lavoie said careful hand hygiene and other COVID-19 protective measures will help guard against RSV as we wait to see how widely it spreads in Canada.

"Things are going to stabilize again, but as we enter into this transition, I think people need to be vigilant," he said.

But that's not all 

Chagla said other illnesses returning this fall include the Norwalk virus, which causes diarrhea, nausea and vomiting. It often gets better very quickly, but can spread quickly through families and people living in close quarters. 

There have also been recent cases of West Nile virus, he said, which can lead to anything from mild symptoms, to a flu-like syndrome, to meningitis and encephalitis. Chagla said if symptoms are accompanied by confusion, headache or neck stiffness, seek medical care.

A man sips his drink while sitting in environmentally friendly physical distancing circles at Trinity Bellwoods Park in Toronto back in May 2020. Physical distancing and other public health measures to slow the spread of COVID-19 also did the same for many other common viruses in Canada. Experts say some of those viruses are making a comeback this fall. (Nathan Denette/The Canadian Press)

Cases of Lyme disease have also been found in Canada over the past few months, he said.

"Our appreciation for the outdoors has been great, but unfortunately means that a lot of people are meeting these ticks where they are."

Because of its similarity to COVID-19 and other viruses, it might get missed. Giving your doctor a detailed history of recent activity can help with diagnosis, he said.

Wash your hands, stay home when sick 

Unlike COVID-19, it's quite common to catch enterovirus and rhinovirus from contact with surfaces, so hand hygiene is as important as ever, said Chagla.

If you catch a cold, he advises staying home and waiting for your symptoms to settle down. Get a COVID test if you develop a fever and respiratory symptoms.

To avoid burdening the health-care system, he also recommends getting a flu shot when it's available. Even those who aren't as vulnerable will likely want to avoid the testing and isolation that comes with respiratory illnesses during the pandemic. 

"Influenza is not only a serious outcome for some, but it's an annoying outcome for others in the context of COVID-19," he said.

Most causes of respiratory tract infections are viral, but bacterial infections need antibiotics, he said. Prolonged illness can be a sign that a doctor's visit is needed. If symptoms persist for a week or more, or continue to get worse, Chagla said, it may be time for a chest X-ray.

Written and produced by Rachel Sanders

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