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Winter in Canada tends to lead to more virus spread thanks to increased time spent with others indoors, as well as the drier, colder air. Some of the most common illnesses seen during the winter months are the flu, colds, respiratory syncytial virus (RSV) and now COVID-19.

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Healthcare system

What is the difference between flu, cold, RSV and COVID-19?

Any number of viruses are in circulation during “flu season,” which generally takes place from November to March. While each of them can cause different illnesses, the symptoms often overlap, which means you may not know which one you have.

What are the symptoms of flu, cold, RSV and COVID-19?

In general, influenza viruses lead to worse symptoms than colds. Flu symptoms can include fever, aches, chills and fatigue, while colds are often characterized by a runny nose, sneezing, sore throat, cough and body aches. Young children and older adults can experience severe illness as a result of the flu.

Respiratory syncytial virus, or RSV can also lead to cold-like symptoms. But RSV can cause severe illness in babies and children under two as well as older adults, who may require hospital admission and oxygen support.

COVID-19 and its variants continue to circulate across Canada. The virus often causes a slew of respiratory symptoms similar to other cold viruses, which means people may not know they have COVID unless they take a rapid test (and even then, the test's accuracy is not guaranteed). Unlike other respiratory viruses, COVID-19 has not yet settled into a predictable seasonal pattern. It can also cause severe illness in at-risk groups, including people who have not been vaccinated, older adults, pregnant women and those with underlying medical conditions.

What are treatments for flu, cold, RSV and COVID-19?

There are no evidence-based treatments that can reduce the severity or length of most cold viruses. In general, rest, fluids and time are what health care professionals recommend. For people who are more at risk, antiviral drugs are available to protect against severe illness linked to the flu and COVID-19.

Are there vaccines for flu, cold, RSV and COVID-19?

There are no vaccines to protect against many common cold viruses. But there are effective, safe vaccines available for the flu, RSV and COVID-19. This year’s flu vaccine is a good match against H1N1, the dominant strain in circulation. A new monoclonal antibody to protect older adults against severe illness linked to RSV has been approved, but is not yet widely available. Health Canada announced on Jan. 4 that it has also approved a new RSV vaccine to protect older adults and infants, through maternal immunization,against severe RSV outcomes.

How long are you contagious with these illnesses, and do you know when you're not?

In general, people are most contagious during the first few days of illness, but can continue to spread infections for days after their symptoms clear up.

What are ways to test for flu or COVID-19?

While it’s possible for hospital labs to test patients for the flu and COVID-19, it’s not feasible to test everyone. Home tests for the flu are not widely available and can be expensive. Rapid tests for COVID-19 were given away for free by governments earlier in the pandemic - check each province's current availability here.

News and updates about flu, COVID, RSV and colds