Here’s what you need to know about Toronto’s ‘early flu season’ and what’s driving cases among children

Abigail Bimman has more on Ottawa’s Children’s hospital sounding the alarm and their advice to the public as Canada’s flu season surges.

A fast-spreading subtype of influenza A known as H3N2 is circulating across the GTA weeks earlier than expected, officials say, with some local health units reporting sharp increases in sick children and rising pressure on hospitals heading into the holidays.

Recent data from Public Health Ontario shows H3N2 is now more common than H1N1, with test positivity climbing across every age group.

Children aged 5 to 11 are currently seeing the highest positivity at 52.3 per cent, followed by adolescents at 46.5 per cent. The early surge aligns with warnings from the World Health Organization, which says influenza A(H3N2) viruses are predominant this season and circulating sooner than typical in the northern hemisphere.

Public Health officials tell CTV News Toronto the early uptick is placing added pressure on healthcare systems at a time of year when capacity is already stretched.

‘We’re seeing a bit of a shift,’ Toronto’s top doctor says

Toronto’s new Medical Officer of Health, Dr. Michelle Murti, says the picture emerging this season differs from what experts typically expect.

“The H3N2 Flu A would typically affect older adults more, and the H1N1 would typically affect younger children more. But we’re seeing a bit of a shift this year, right now we are seeing quite a bit of severity in younger children with the H3N2, and that’s predominantly what we are seeing this year for flu A.”

Murti adds “we’re seeing very little flu B right now.”

Global surveillance echoes that trend. WHO officials note a predominance of influenza A (H3N2) in Canada, the United States, and parts of Mexico, with growing detections of H3N2 subclade K — the same strain seen locally in the GTA.

Earlier onset, tighter hospital capacity

Health officials warn the early spike is landing at the worst possible time for many hospitals already overwhelmed with holiday vacations and tighter staffing.

“Our hospitals are basically always running at 100 per cent or more capacity. We don’t have a lot of give in the system for extra patients coming in. So anything we can be doing to alleviate that…to prevent people from going to the hospital in the first place, that’s really important,” Murti said.

She added that while COVID-19 activity is slowly increasing, “it’s a little bit of a saving grace for us that we don’t have COVID and flu peaking at exactly the same time, because that really puts that extra strain on the healthcare system.”

The early rise of influenza also coincides with early winter blasts seen across the GTA in recent weeks, several of which broke decades-old weather records.

• Toronto’s early snowfall breaks decades-old weather records

What symptoms families should watch for

Murti explains the signs parents should watch for are closely associated with the typical symptoms of flu-related illness.

“Certainly the typical things that people feel with any influenza infection, fever, cough, that really tired feeling, that muscle ache, fatigue, that kind of, hit by a truck, wiped out, type of feeling is very common for whenever you’re infected with flu.”

For young children, she said prolonged or high fever and signs of dehydration should prompt immediate medical attention.

“If they’re not drinking well, if they’re not able to take in fluids or solid like, to eat or drink, those are really concerning signs…to seek medical attention.”

A closer look at Durham and Peel region

Some health units are seeing significant increases in confirmed cases.

Durham Region Public Health reported more than 150 new cases in the past week alone, bringing its total to 373. Almost all of them being influenza A. The virus has been most prevalent in residents over 80 and children under 10.

“Durham Region Health Department is seeing an early rise of Influenza A cases this season,” the agency said, adding, “we have seen a large rise in influenza cases over the past few weeks.”

Officials urged residents to get vaccinated and to take preventive measures such as masking in public places, staying home when sick, and practicing proper cough and hand hygiene.

In Peel Region, Associate Medical Officer of Health Dr. Atiba Nelson said influenza A(H3N2) is now driving more acute care admissions than COVID-19 or RSV.

“Right now we’re seeing a rise in respiratory virus activity in Peel, especially influenza A subtype H3N2,” he said. “Flu is generally higher among kids and adults over the age of 65 compared to other age groups. This year is an early flu season. Flu season tends to happen right around this year, until, I would say, April.”

Vaccines still expected to offer protection

Even with concerns about potential mismatch with the new H3N2 subclade, health officials say the current flu shot still offers strong protection.

“There might be a bit of a mismatch, but we don’t know for sure. We don’t really ever know the full effectiveness until we’re well within the season and can actually measure and see how well that did,” Murti said. ”Now is absolutely the time to get (the flu vaccine). We’re only going to see more of this in the next four to six weeks. So you want to have that protection now.”

WHO guidance supports that message. Officials say current vaccines include H3N2, H1N1, and influenza B, and that a drifted virus does not always mean seasonal vaccines are less effective.

Early international data is also encouraging. Murti cited a U.K. study showing up to 75 per cent protection against H3N2.

Who is most vulnerable right now?

So far, younger children and adults over 65 are seeing the heaviest burden of illness, based on data from Peel, Durham, and Public Health Ontario.

Murti stressed the importance of families acting now.

“Flu is circulating now and it is looking like is pretty severe in children. Make sure that your kids, as well as whole families, are getting vaccinated now, if you haven’t yet. We’re trying to prevent that increase in illness through the holiday period.”