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Influenza (flu)

Learn about influenza, who is at risk, and how it spreads.

About influenza

Influenza, sometimes called the flu, is an infection of the nose, throat, and lungs that is caused by a virus. Influenza is a respiratory illness.

The number of people who get sick with influenza is different year to year. On average each year, more than 12,000 people in Canada have to stay in a hospital because of influenza, and 3,500 people die from it.

Learn more about influenza.

Who is most at risk?

Everyone is at risk of influenza. The time when people are at greatest risk is called influenza season. It generally happens every year starting in late fall and lasting through the winter.

Influenza can make you very sick and lead to other health problems, especially if:

  • You have heart or lung conditions, diabetes, a weak immune system, a lot of extra weight, or other health problems.
  • You live in a care facility, such as a nursing home.
  • You are under age 5 years.
  • You are age 65 years or older.
  • You are pregnant.
  • You are an Indigenous person.

How it spreads

Influenza can spread in the following ways:

  • An infected person sneezes, coughs, or even talks.
  • You breathe in the virus.
  • You touch something that has the virus on it (such as hands or a doorknob), then touch your eyes, mouth, or nose.

Air droplets

Contaminated objects

Touching eyes, nose or mouth

You can spread influenza before symptoms start.

COVID-19, influenza, and colds

Influenza is caused by a different virus than COVID-19, the common cold, and gastrointestinal illness (sometimes called the stomach “flu”). Although the symptoms of these diseases can be similar, there are differences:

  • The common cold usually does not include a high fever.
  • Gastrointestinal illness does not include a cough, sore throat, or runny nose.
  • COVID-19 sometimes involves a loss of smell or taste.
  • There is no vaccine for the common cold and gastrointestinal illness.
Current as of: September 1, 2023
Author: Provincial Immunization Program, Alberta Health Services
Our work takes place on historical and contemporary Indigenous lands, including the territories of Treaty 6, Treaty 7 & Treaty 8 and the homeland of the Métis Nation of Alberta and 8 Métis Settlements. We also acknowledge the many Indigenous communities that have been forged in urban centres across Alberta.