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Frequently Asked Questions – Influenza

What is influenza ("the flu")?
Seasonal influenza, or "the flu," is a common infection that affects the nose, throat and lungs that can spread easily among humans.   Flu strains change from year to year, and that’s why it’s important to get an annual flu shot.

How is it spread?
The influenza virus spreads through contact with droplets that have been coughed or sneezed  by someone who has the flu. You can also get the flu by shaking hands with an infected person or by touching contaminated surfaces, and then touching your own eyes, nose or mouth.

What are the symptoms of flu?
The flu and the common cold have similar symptoms with the flu being more severe.
Flu symptoms almost always include:

  • A sudden onset of fever or feeling feverish
  • A cough and/or sore throat

Flu symptoms commonly include:

  • A runny or stuffy nose
  • Headaches and/or body aches
  • Chills
  • Fatigue (feeling tired)
  • Decreased appetite
  • Nausea, vomiting, and/or diarrhea (mostly in children)

How is a cold different from influenza?
A cold is a mild infection of the nose and throat that is caused by a variety of viruses. Cold symptoms (e.g runny nose, sneezing, cough and sore throat) may linger but remain mild. A person with a cold will not usually have a fever, nausea, vomiting or diarrhea.

How serious is the flu?
Most people recover from the flu in about a week. However, influenza may be associated with serious complications such as pneumonia (especially in infants, children, the elderly, and anyone with chronic health conditions such as diabetes or cancer). On average, the flu and its complications send about 20,000 Canadians to hospital every year, and on average 2,000 to 8,000 Canadians die.

How does the flu shot protect me?
When you get the flu shot, your body's immune system develops protection (antibodies) against the strains of the virus in the vaccine. The antibodies help prevent infection or reduce the severity of the illness. Different flu viruses can affect people every year, so the vaccine needs to be updated annually. This is why it is important to be immunized each fall.

What are some ways to reduce the risk of catching or spreading the flu?

  • Get your flu shot every year.
  • Wash your hands often with soap and warm water for at least 20 seconds, or use alcohol-based hand sanitizer if soap and water are not available.
    • Wash your hands:
      • before and after eating
      • after you have been in a public place
      • after using a washroom
      • after coughing and sneezing
      • after touching common surfaces
  • Keep your hands away from your face.
  • Cough and sneeze into your arm, not your hand. If you use a tissue, dispose of it as soon as possible and wash your hands.
  • Keep common surface areas - for example, doorknobs, light switches, telephones and keyboards - clean and disinfected.
  • Eat healthy foods and stay physically active to keep your immune system strong.
  • Keep doing what you normally do, but if you get sick, stay home from school and work until you are feeling better and able to fully participate in regular activities.

Encourage all members of your household, especially children, to follow these practices.

Who should receive the seasonal flu shot?
It is recommended that all Canadians over the age of 6 months get the seasonal flu shot every year.  Certain groups are recommended as a priority for influenza immunization:

  1. People at high risk of complications or hospitalization from the flu, including:
    • Children and adults (including pregnant women) with chronic health conditions, such as cancer, heart and lung disease, diabetes and asthma
    • People who are morbidly obese (BMI of 40 or higher)
    • People of any age who are residents of nursing homes or long-term care facilities
    • People 65 years of age and older
    • All children 6-59 months of age
    • Healthy pregnant women
    • Aboriginal peoples
  2. People in close contact with individuals at high-risk for complications (e.g. health care workers, and household contacts of those at high risk)
  3. People who provide essential community services (e.g. firefighters, police officers)
  4. People in direct contact with avian influenza-infected poultry during culling operation

What is an antiviral?
An antiviral is a medicine that you take by swallowing a pill or liquid, or by breathing it in. The medicine works by either destroying the virus or interfering with its ability to grow and reproduce. It does not stop you from getting sick by providing immunity.  It can be given to someone when they are sick to reduce symptoms, to shorten the length of illness and to minimize serious complications.

How is seasonal flu different from pandemic flu?
An influenza pandemic is declared when a new strain of flu virus emerges that has never been seen before and begins to spread quickly around the world.  For example, in Spring 2009, a new strain of the influenza virus, the H1N1 virus, caused a pandemic.  As it was a new strain of influenza and because humans had little to no natural immunity to this virus, it caused serious and widespread illness.

Since the end of the 2009 H1N1 pandemic, the H1N1 influenza virus continues to circulate in Canada at low levels and is one of the viruses that the annual flu shot protects against.

What is avian (“bird flu”) or swine influenza?
Avian influenza is an influenza A virus that naturally circulates in birds.  Swine influenza is an influenza A virus that naturally circulates in swine, or pigs.  Human infections with avian or swine flu are a result of contact with infected animals.

Symptoms of avian or swine influenza in humans are similar to those of seasonal flu and can include fever, cough, runny nose and possibly body aches, nausea, vomiting or diarrhea.

For more information on pandemic influenza, visit