Flu (influenza): Prevention and risks

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How the flu spreads

The flu is an infection of the nose, throat and lungs. It's caused mainly by 2 types of viruses:

  1. influenza A
  2. influenza B

The flu spreads very easily from person to person. Even before you notice symptoms, you may spread the virus to others. If you have the virus, you can spread it by:

  • talking
  • sneezing
  • coughing

These actions release tiny droplets that contain the flu virus into the air.

You can become infected if these droplets land on your:

  • eyes
  • nose
  • mouth

Infection can also happen if you touch any of these body parts after touching surfaces contaminated by infected droplets. Frequently touched surfaces and objects include:

  • toys
  • toilets
  • phones
  • door handles
  • bedside tables
  • television remotes
  • electronics and tablets

Preventing the flu

The flu shot is safe and is the best way to prevent the flu. Most people don't have any side effects. Severe reactions are very rare.

You can't get the flu from the flu shot. Scientists have developed different types of vaccines, which are:

  • non-live vaccines that contain killed (inactive) viruses or their parts
  • live vaccines that contain live but weakened (attenuated) viruses

Get the flu shot

Everyone 6 months of age and older should get the flu shot. Getting a flu shot is a simple action that can save lives by:

In addition to getting the flu shot, you can also protect yourself and those around you from the flu and COVID-19 by:

  • not touching your eyes, nose or mouth with unwashed hands
  • washing your hands often with soap and warm water for at least 20 seconds
    • if soap and water aren't available, use a hand sanitizer containing at least 60% alcohol
  • coughing and sneezing into the bend of your arm, not into your hand
  • cleaning and disinfecting surfaces that a lot of people touch, such as:
    • phones
    • doorknobs
    • television remotes
  • staying home if you're sick
    • if you start to develop symptoms, isolate yourself from others and contact a health care provider or local public health authority

It can be hard to tell the difference between symptoms of the flu and COVID-19. You can only confirm if you have flu or COVID-19 with a test. If you have symptoms of the flu and haven’t received a negative COVID-19 test, follow COVID-19 prevention measures to help keep others safe.

When the flu is a risk

In Canada your risk of getting the flu is higher in the:

  • late fall
  • winter

Your risk is lower the rest of the year.

Who is most at risk

Everyone is at risk of getting the flu. The flu is among the 10 leading causes of death in Canada. Each year in Canada, the flu causes an estimated:

  • 12,200 hospital stays
  • 3,500 deaths

Some people are at a higher risk of flu-related complications. These include:

People with health conditions

These conditions can affect a person's immune system and can make it harder to fight off infections, such as:

  • cancer and other immune compromising conditions
  • diabetes
  • heart disease
  • lung disease
  • anemia
  • obesity
  • kidney disease
  • neurological or neurodevelopmental conditions
  • children up to 18 years of age undergoing treatment for long periods with acetylsalicylic acid (ASA)

Getting the flu can also worsen the symptoms associated with some of these health conditions.

People 65 years and older

The immune system changes with age and this can make it harder for the body to fight off infections. People over the age of 65 are also more likely to have health conditions which can worsen if they get the flu.

People who live in nursing homes or other long-term care facilities

The flu spreads quickly, especially in communal spaces. Residents are also more likely to have health conditions which can worsen if they get the flu.

Children under 5 years of age

Because of their age, their immune system is still building immunity to fight off serious infections.

People who are pregnant

During pregnancy, the body goes through many changes that can affect the immune system, heart and lungs. These changes can make it harder for the body to fight off infections.

People who get the flu shot during pregnancy pass on protection to their baby. This is especially important, as babies younger than 6 months can't get vaccinated against the flu. Getting your flu shot can help protect your baby from the flu after birth.

Learn more about:


  • People who have reduced access to health care, such as vulnerable populations like those experiencing homelessness or those with disabilities
  • People who are at an increased risk of illness because of living conditions, such as those:
    • living in shelters who experience overcrowding
    • who have limited access to facilities for personal hygiene
    • persons with disabilities who might have limited capacity to understand or perform personal hygiene practices

Some people are more likely to spread the flu to those at high risk of complications. They include:

  • caregivers
  • child care providers
  • health care providers
  • family and other household members
  • those who provide services in closed or relatively closed settings to people at high risk, such as workers in long-term care facilities or crew on a ship

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