​​​​​​​​What is influenza?

Influenza (sometimes called the flu) is an infection of the nose, throat, and lungs (respiratory tract) that is caused by a virus. Influenza can happen any time during the year, but most cases happen in the winter months.

You may also hear influenza called flu, bird flu, or H1N1. All of these mean the same thing as influenza, and the information below applies to all of them.

How is influenza spread?

Influenza is spread through the air. The virus gets in the air when someone with the disease coughs, sneezes, or even talks. People who breathe in the virus can get sick. It can also be spread by touching objects that have been coughed or sneezed on by someone with the virus.

How serious is influenza?

Most people who get sick with influenza get better. 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 the hospital because of influenza, and 3,500 die from it.

​​You have a higher risk of complications (serious health problems) from influenza if you:

• are less than 5 years of age
• are pregnant
• are 65 years or older
• have chronic (long-term) health problems, such as heart or lung conditions, diabetes, a weak immune system, or a lot of extra weight
• live in a long-term care facility, such as a nursing home
• are Indigenous

Complications of influenza can include pneumonia (a type of lung infection), ear and sinus infections, and dehydration. Influenza can also make chronic medical problems (such as congestive heart failure, asthma, diabetes) worse.

What are the symptoms of influenza?

The symptoms of influenza are:

• fever that starts suddenly
• chills
• sore throat
• cough
• headache and muscle aches
• loss of appetite (not feeling hungry)
• feeling tired

Other symptoms may include feeling sick to your stomach (nausea), vomiting (throwing up), or having loose stool (diarrhea). These are more common in young children.

You can spread influenza (be contagious) the day before you have symptoms and for up to 7 days after symptoms start.

How can I help prevent influenza?

• Get the influenza vaccine. The vaccine works very well to protect people from getting sick with influenza. You need to get immunized every year because the influenza viruses change. A new vaccine is made each year to protect against the viruses most likely to cause illness in that year. The best time to get immunized is October or November. You can get immunized any time during influenza season, which​ starts in late fall and lasts through the winter.
• Wash your hands with soap and water or clean your hands with a hand sanitizer that has alcohol in it.
• Cover your mouth and nose with your arm or a tissue when you cough or sneeze.
• Stay home and rest when you’re sick.

What is the difference between influenza, COVID-19, a cold, and a gastro-intestinal (GI) illness?