Coronavirus, the flu or the common cold? Here’s what to know

Cold, flu or COVID-19? How to tell the difference

Cold and flu season is officially underway in Canada, and with the on-going global pandemic, a sore throat or runny nose may have people wondering if they have COVID-19.

As coronavirus cases continue to rise, it’s important to be able to tell the difference between the symptoms of a common cold, influenza and COVID-19. But this also may be difficult to do.

Influenza, the common cold and COVID-19 are all contagious respiratory illnesses, and are caused by different viruses. According to the U.S. Centers for Disease Control and Prevention, COVID-19 is caused by infection with a new coronavirus (called SARS-CoV-2), the flu is caused by infection with influenza viruses and the common cold is caused by countless viruses such as rhinovirus and coronavirus.

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Dr. Jerome Leis, medical director of infection prevention and control at Sunnybrook Health Sciences Centre, said there are subtle differences between all three sicknesses, but they can be difficult to determine.

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“It’s unfortunately impossible to reliably distinguish the cold from a virus-like influenza or COVID-19,” he said. “The symptoms are just too non-specific. And we know from COVID-19 that there is a wide spectrum of different presentations, (including) extremely mild symptoms that could resemble the common cold. So, unfortunately, we can’t distinguish those without testing.”

Here are some differences in the illnesses.


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The main symptoms of COVID-19 are fever, a persistent dry cough, and fatigue, according to Health Canada.

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Other symptoms include shortness of breath, a loss of sense of taste and smell, and a rash on skin or discolouration of fingers or toes. This can also be accompanied by aches and pains, a headache and gastrointestinal symptoms (such as abdominal pain, diarrhea, or vomiting).

Upper respiratory symptoms, like runny nose and sinus congestion, are very uncommon in COVID-19.

“There are some symptoms that might be potentially distinguishing like the loss of taste or smell that’s widely reported … (or) change in the skin that might occur. But I really would not rely on those for people to self-diagnosis with COVID-19,” Leis explained.

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The flu

The most common symptoms of influenza are fever, fatigue, a dry cough, aches and pains and headaches. Some people may experience a sore throat and a runny or stuffy nose. Diarrhea can sometimes occur in children.

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Sneezing is usually not associated with the flu, but shortness of breath can develop.

Because COVID-19 and the flu tend to affect the lungs and lead to severe complications, the two illnesses can be very difficult to distinguish, according to Dr. Zain Chagla, an infectious disease expert with McMaster University.

“Unfortunately muscle pains, cough, fever, nausea, shortness of breath, all of those fit COVID-19. And they fit influenza. So from a clinical standpoint, they’re very hard to distinguish,” he said.

Common cold

While you may feel miserable when you have a cold, the symptoms are generally mild compared to the other viruses.

The symptoms tend to stay in the upper airways, meaning you’re most likely to experience a stuffy or runny nose, sneezing and a sore throat, according to Health Canada.

While a fever is common with COVID-19 and the flu, it is rarely a symptom of a cold.

Make sure to get tested

Leis warned that people should not solely rely on the symptoms above for self-diagnosing.

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“People really need to get tested if they have any symptoms that could range from a common cold to more flu-like symptoms because it could definitely be coronavirus,” he said. “I think the similarity between COVID-19, the flu and even the common cold really reinforces the importance that we all follow public health measures to prevent all of them.”
Leis said because symptoms can be so similar, it’s important to self isolate “immediately” at the onset of sickness. 
And as the number of COVID-19 cases continues to grow across Canada, he stressed the importance of social distancing, frequent handwashing, keeping to a tight social bubble and getting the flu shot.
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“Those are the most important aspects of being protected,” he added.

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