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What is influenza (flu)?

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Influenza (flu) is a contagious lung disease caused by the influenza virus. This is a different virus than the one that causes COVID-19. There are big waves of flu cases every year, usually in the fall and winter. 

The flu can cause cough, muscle aches and fever. It spreads quickly and easily to other people, especially when we are close to each other indoors.  

Most people get better from flu infections after about a week, but some people get sick enough to need hospital care. Babies, Elders, and people living with chronic diseases are more vulnerable to get very sick and suffer severe complications from the flu.  

Getting a yearly flu vaccine (flu shot) is your best protection against the flu. It can save lives by protecting you if you are exposed to the virus, preventing you from getting sick with the virus, and protecting people close to you because you are less likely to spread the virus. 

Stay home if you are sick

Flu shares similar symptoms with COVID-19, making it difficult to tell them apart. If you are experiencing any flu-like symptoms, it is important to stay at home and complete this self-assessment tool to see if you need a COVID-19 test and if you need to isolate. 



The flu is very contagious and spreads quickly and easily to other people. You may be passing the flu on to others before you even know you are sick. 

We are all at risk of getting the flu, but the flu will not affect us all the same way. Most people who get the flu will get better quickly, sometimes after only a few days or up to 2 weeks. However, some people will get very sick and need hospitalization. Even healthy people may have serious problems from the flu.  

Complications such as pneumonia and respiratory failure are possible, and flu may also worsen existing chronic health conditions such as asthma. Flu may also trigger other serious complications such as inflammation of the heart, brain, or muscle tissues, and multi-organ failure. 

It can also be deadly – in Canada, on average, close to 3,500 people die each year of the flu. This is more common in people who are elderly and who are living with chronic diseases like diabetes. 


Some people are at higher risk of health complications from flu: 

· Elders 75 years old or more 

· People with a chronic disease such as: 

  • cancer or other conditions that compromise the immune system 

  • diabetes 

  • heart disease 

  • lung disease 

  • anemia 

  • obesity 

  • kidney disease 

  • liver disease 

  • neurological or neurodevelopmental conditions 

· People on immunosuppressive treatments (like corticosteroids, auto-immune disease treatments, etc.) 

· Pregnant women 

· People living in long-term care homes 

· Babies under the age of 6 months old 

Explore more about Infections

Infections happen when germs enter someone’s body, and start to make the person sick. Some infections cause sickness in the whole body (like getting a fever, body aches, coughing) and others might affect only one body part (like getting an ear infection).

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