RSV infections surge as hospitals brace for return of ‘normal’ respiratory virus season

On a weekday afternoon, coughs and cries echo throughout the brightly lit waiting room of the Just for Kids Clinic at St. Joseph’s Health Centre in Toronto.

It’s clear this year’s respiratory virus season is already underway, said Dr. Anne Wormsbecker, chief of pediatrics at the hospital, one of three health-care sites making up Unity Health Toronto. While most children who arrive for outpatient appointments aren’t given tests to figure out which virus is making them sick, she said inpatient units where patients are tested upon admission are seeing a striking trend.

“In the last couple of weeks, the respiratory syncytial virus — or RSV — has just shot up,” she said.

Country-wide data also shows RSV is on the rise. So far, 1,220 cases have been detected since late August, with roughly five per cent of tests coming back positive, according to the most recent respiratory virus report from the Public Health Agency of Canada (PHAC).

“Activity of RSV is increasing and slightly above expected levels for this time of year,” the report noted.

The virus usually causes common cold symptoms, but can turn serious among both the young and old.

SARS-CoV-2, the virus that causes COVID-19, is still circulating as well, and influenza activity is also increasing, although still within the typical levels for November, PHAC data shows.

After a roller-coaster of viral dynamics during the pandemic — including a period where influenza nearly vanished, followed by an unusual RSV surge last year — some say this season could mark a return to relative normalcy, but with SARS-CoV-2 now firmly in the mix.

However, “normal” doesn’t mean it’ll be smooth sailing for either the public or Canada’s strained health-care teams, said McGill University infectious diseases specialist Dr. Donald Vinh.

“The pattern that we’re seeing is not new, but it’s the return of what we’ve been used to — with COVID now superimposed,” he said.

Pandemic caused unpredictable viral dynamics

In Canada, RSV typically poses a problem from October onward, said Vinh, with flu following behind, then possible subsequent waves of infections later in the season.

“That’s actually been the norm, for years, if not decades,” he said. “But COVID wiped that out — not the public health response to COVID, but [the virus] itself.

“It was such a transmissible virus that it smothered the transmission of other viruses until we had a partially immune population to COVID.”

Medical experts call that phenomenon “viral interference” — it’s what happens when a virus like SARS-CoV-2 pushes out other pathogens at a population level for a period of time, possibly because widespread infections keep people’s immune systems on high alert. 

Other researchers have argued society-wide public health measures such as mask-wearing and social distancing likely mattered more in keeping other viruses at bay. Indeed, after COVID restrictions were lifted, infections from other threats such as RSV began to surge. 

Wormsbecker said health-care teams like hers are bracing for another winter where high numbers of children are hospitalized. “We’re certainly hoping not to see that again this year,” she added, “but that’s what we’re preparing for.”

Quebec’s RSV reports are rising quickly, Vinh said, while data from the B.C. Centre for Disease Control shows in that province, “RSV test positivity continues to increase and is higher in children.”

One Toronto pediatric clinic is seeing visits for a variety of respiratory ailments are spiking fast.

“Our baseline is about 300 visits a day, and now in the past two weeks we bumped up to 400 patients a day,” said Dr. Daniel Flanders of Kindercare Pediatrics.

Physicians are also concerned about the impacts on seniors as these viruses spread to older populations. 

“We’re seeing some RSV outbreaks in long-term care facilities, but compared to COVID they’re way, way down,” said Dr. Allan Grill, chief of family medicine at Markham Stouffville Hospital, north of Toronto. “But what’s to come in the next few months is hard to predict.”

As for flu, more than 180 influenza-associated hospitalizations have already been reported since late August, PHAC said. Adults aged 65 and older made up slightly more than half of those reported hospitalizations.

“The good news is that, in the Southern Hemisphere — which gets an influenza season earlier than we do here in North America and Canada — they didn’t get an overwhelming flu season like we’ve seen in the past,” Grill noted. “So, we’re hoping that the same will happen up here.”

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Vaccines available for COVID, flu, RSV

Vinh warned that many Canadians could still get hit hard, given varying levels of immunity to each virus within the population. The majority of the public has already been exposed to SARS-CoV-2, vaccinated against it, or both, Vinh noted, but there are also “populations that have not built up any partial immunity to RSV or flu who will be contracting either virus for the first time.”

The silver lining, he added, is that Canada is still at the beginning of the season, which means there is time to mitigate dire consequences through widespread vaccination, including with updated COVID vaccines that better match circulating strains of the virus.

Health Canada also approved an RSV vaccine earlier this year for adults aged 60 and up. Many Canadians will have to pay out of pocket — at a cost of upwards of $200 — though Ontario is also providing it for free to residents of long-term care facilities.

“It is not too late to get your COVID vaccine if you haven’t been updated, or your flu shot if you haven’t gotten it,” Vinh said.