Flu season has started in Canada. How does it differ from COVID, allergies or a cold?

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It's that time of year again: Flu season has officially arrived in Canada, according to the federal public health agency.

On Friday, the Public Health Agency of Canada (PHAC) confirmed the news, noting that flu cases have stared rising across the country. As of Nov. 25, 7.5 per cent of people tested for influenza across Canada were positive. Moreover, the rate of tests that came back positive remained higher than five per cent for two consecutive weeks.

"At the national level, influenza activity has crossed the seasonal threshold, indicating the start of influenza season," the PHAC said in its weekly FluWatch report.

While not all provinces and territories are reporting a five per cent positivity rate yet, it's only a matter of time for those areas of Canada to catch up.

Moreover, a new COVID-19 subvariant called HV.1 is spreading across the country. It's part of Omicron lineage, and while it might be too early to tell if it'll be a major cause of concern this season, it's a reminder COVID-19 is still present.

"It's the newest Omicron on the block, it's the one that seems to be winning the race right now, but it's one of a handful of other respiratory viruses that are circulating," University of Saskatchewan virologist Angela Rasmussen told Yahoo Canada late last month.

"This is kind of what we should maybe expect to be our new normal for cold and flu season going forward."

Overlapping symptoms between COVID-19, RSV, the flu and colds can make taking care of yourself confusing. Read on to know what's happening with all the respiratory illnesses, and how to tell the symptoms apart.

What can you expect from cold, flu and COVID this winter?

According Dr. Andrew Pinto, this season could be "fairly severe" for illnesses in what some are calling a tripledemic.

"Many of us in public health and in practice are worried that we're going to have a fairly severe respiratory illness season with a mix of COVID, influenza, and other viruses like RSV," he told Yahoo Canada in October.

Pinto, a public health specialist at the University of Toronto and the lead investigator of CanTreatCOVID, said experts look at the southern hemisphere to detect trends in seasonal illnesses, as they have them earlier on.

"They had quite a lot of COVID circulating, about two-thirds COVID and then one-third other viral illnesses," he said.

"One of the reasons I think we're very worried is that many people in Canada, and in similar countries, it's been quite a while since they either had a COVID infection or a vaccine. And so there's likely more susceptibility in the population to the latest circulating COVID strain."

What's the difference in symptoms between COVID, flu, allergies or a cold?

Pinto explained it's "very, very hard" to differentiate between the symptoms of these respiratory illnesses, especially COVID-19 and influenza.

"There's a lot of overlap. ... There may be some slight differences, particularly that we saw early in the COVID pandemic was around the loss of smell and taste. That still is somewhat of a hallmark of of COVID."

He also added the persistence of symptoms after the initial infection is more common with COVID-19 than other viruses.

"It's important to note COVID is still evolving, and we don't know how new strains will really act and what kind of symptoms they will give us."

What to do if you have overlapping symptoms?

Pinto said a "really important message" is that anyone who is experiencing respiratory illness — including the symptoms above — should do an at-home test for COVID-19.

"These test kits are being made available to many provinces and territories, for free through grocery stores, through pharmacies, through health clinics.

"Some of the benefits of doing a test to see if you have COVID or not are, it helps you reduce the spread to other people, because it will change kind of your behavior," said the Upstream Lab director.

It can also help those who are feeling sick and might need to take time off from work. "Potentially, if you develop long-COVID and need to need to seek disability, accommodation or financial support, that can help with your claim," he added.

He claimed in the future, we could see multi-pathogen tests available to narrow down whether an illness is COVID-19, influenza or RSV.

What can Canadians do to stay safe this winter?

Canadian health officials and doctors are advising of COVID-19 best practices this winter, which can also help curb the spread of other viruses.

While the country no longer has testing or masking mandates in place like it used to, there are still protocols Canadians can follow.

According to Pinto, the most important move is getting vaccinated.

"We know that a lot of people are tired of, of the pandemic and want to just move on," he began, before adding COVID is here to stay.

"Getting one's COVID shot is really important, getting your influenza vaccine, and if you're eligible, getting your RSV vaccine is going to be important to helping protect oneself."

Pinto, also encouraged anyone who does get infected with COVID-19, to reach out to CanTreatCOVID within the first few days of infection.

"We really still don't have a good sense of what works and for whom to treat COVID when people are acutely infected. So we're doing this study. ... We're studying which treatments work and for whom," he explained.

"It's a really important way to help figure out how we can not only treat acute COVID, but also reduce long COVID as well."

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