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Influenza (or “the flu”) is a respiratory infection caused by influenza A and B viruses. Learn about influenza, where to get free flu immunization, flu vaccines and more.

Nasal spray flu vaccine

The nasal spray flu vaccine is only available for private purchase during the 2020-2021 influenza season.

Influenza (commonly known as “the flu”) is a respiratory infection caused by the influenza A and B viruses. Do not confuse it with "stomach flu" and other illnesses. People of all ages, including the young and healthy, can be affected by the flu.

How flu spreads

The flu is spread from infected persons through:

  • Coughing
  • Sneezing
  • Touching surfaces that have been contaminated by an ill person (such as toys, doorknobs, utensils or unwashed hands) and then touching your eyes, nose or mouth

Flu symptoms

Typical flu symptoms include the sudden onset of:

  • Fever
  • Headache
  • Muscle aches and pains
  • Fatigue
  • Cough
  • Loss of appetite
  • Runny nose
  • Watery eyes
  • Throat irritation

Children can also get:

  • Earaches
  • Nausea
  • Vomiting
  • Diarrhea

Most people recover within a week to ten days, but the cough and fatigue can take much longer to resolve.

Risks from complications

Most us of are at risk of infection with the influenza virus. People at greater risk of complications from flu include:

  • Adults and children with certain chronic medical conditions including:
    • Anemia
    • Asthma
    • Lung, heart and kidney disease
    • Neurologic or neurodevelopment conditions
    • Diabetes
    • Cancer
    • Weakened immune systems due to disease or medication
    • Morbid obesity
  • Residents of nursing homes and chronic care homes
  • Persons 65 years of age and older
  • Children under 5 years old
  • Pregnant women
  • Indigenous peoples

Protecting yourself and others from the flu

Follow these steps to protect yourself and others from influenza:

  • Get the flu vaccine to protect yourself and others.
  • Wash your hands often with soap and water for at least 15 seconds.
  • Keep an alcohol-based hand sanitizer handy at work, home and in your car.
  • Cough and sneeze into your sleeve or a tissue, not your hand. Dispose of tissues immediately.
  • Clean and disinfectcommonly touched surfaces and items.

Common cold versus the flu

Colds, vomiting, diarrhea (often referred to as "stomach flu") and other viral infections are often confused with the flu but different viruses cause them.

Symptoms Cold Influenza
Fever Rare Usual, high fever (39°C/102°F - 40°C/104°F); sudden onset, lasts 3-4 days
Note: The elderly and people who have a weakened immune system might not develop a fever.
Headache Rare Usual, can be sudden
Muscle aches & pains Sometimes, generally mild Usual, often severe
Tiredness & weakness Sometimes, generally mild Usual, severe, might last 2-3 weeks or more
Extreme fatigue Unusual Usual, early onset, can be severe
Runny, stuffy nose Common Common
Sneezing Common Sometimes
Sore throat Common Common
Cough/chest discomfort Sometimes, mild to moderate Common, can become moderate to severe; cough might last for weeks
Complications Can lead to sinus congestion or infection, and ear aches*** Can lead to pneumonia, can worsen a current chronic condition, can be life threatening

*** Colds do not generally result in serious health problems, such as pneumonia or bacterial infections.

Note: Children might also experience the croup, ear infections, nausea, vomiting and diarrhea when they have influenza – symptoms that are not common in adults.

What to do if you get the flu

There are several steps you can take to help yourself and to help reduce the spread of illness to others:

  • Stay home and avoid contact with others if you do not feel well! If you can, sleep in a separate room from others until you are well.
  • See your family doctor if illness persists or becomes worse, or call Telehealth at 1-866-797-0000, TTY 1-866-797-0007 to speak with a registered nurse.
  • Avoid visits to long-term care homes, hospitals and retirement residents if you have been ill or have had contact with someone who is ill. Please help protect frail persons and other individuals at high risk.
  • Cough into your sleeve or a tissue and not your hands if you have a cough. Dispose of the tissue immediately, and make sure to wash your hands.
  • Clean and disinfect all contaminated surfaces and frequently touched surfaces, such as doorknobs, faucet taps and toilet handles.
  • Wash your hands frequently with soap and water to protect yourself from getting infected. Use an alcohol-based hand rub when soap and water are not available.
  • Drink a lot of fluid.
  • Get plenty of rest.
  • Take an analgesic (aspirin or acetaminophen) to relieve head and muscle aches. Children and teenagers who have the flu should avoid aspirin unless specifically directed by a physician.

The flu vaccine is an immunization made each year to protect against strains of influenza virus that are expected to be circulating in the community in the upcoming influenza season. The vaccine stimulates your body’s immune system to build antibodies against influenza, making it stronger and ready to fight off the illness before it starts.

There is a free flu vaccine:

  • For people 6 months and older of that provides protection against four common strains of flu virus
  • Halton residents 65 and older are eligible to receive either the regular quadrivalent (4-strain) or high-dose trivalent (3-strain) flu vaccines.

It is best to talk to your doctor about any questions you may have about the flu vaccine.

Your record of protection: After you get your immunization, you will be given a written record. Tell your doctor the date you received the influenza vaccine.

Flu vaccine for children

The expert advisory committee on vaccines in Canada (National Advisory Committee on Immunization (NACI)) recommends that children 6 months through 17 years receive a vaccine that protects against four strains of flu virus.

The traditional vaccine injection given in the arm is safe and works well to prevent influenza infection in children. FluMist®Quadrivalent (AstraZeneca) is not available for use in Canada for the 2019-2020 influenza season. Therefore, no nasal spray influenza vaccine (LAIV) alternative is available in Canada for this season.

Safety and side effects

The flu vaccine is safe. Most people who get the vaccine have either no or mild side effects. Mild side effects, which occur within 1 - 2 days after vaccination, include soreness or redness or swelling at the injection site.

Life-threatening allergic reactions are very rare. In very rare cases, the flu vaccine has been associated with:

Guillain-Barré Syndrome (GBS)

  • GBS is a very uncommon disease that causes muscle paralysis.
  • The risk is about 1 in one million doses of vaccine given.

Ocular respiratory syndrome (ORS)

  • In 2000-2001, a small number of people who received the influenza vaccine developed ORS.
  • ORS can cause red eyes, cough, chest tightness, difficulty breathing, hoarseness, sore throat and swelling of the face.
  • Symptoms occur within 24 hours and resolve within 48 hours.
  • Persons who experienced ORS in the past might safely have the flu vaccine but should talk to their healthcare provider before being immunized.

Protection against the flu

Influenza vaccine effectiveness can vary from year to year and among different age and risk groups. It cannot protect you from other types of viruses circulating in the fall/winter months that can cause illness much like influenza. The body needs 2 weeks to build up protection to the flu virus after you receive immunization; protection might last up to 1 year.

Who should get the vaccine

The National Advisory Committee on Immunization (NACI), which advises the Public Health Agency of Canada, recommends the flu vaccine for everyone 6 months of age and older. It is especially recommended for persons:

  • At high risk for complications of flu
  • Who might spread influenza to high-risk people
  • Who provide essential community services

Who should not get the vaccine

The Health Department will not give the vaccine at clinics to anyone who:

  • Has had severe allergic reaction to a past influenza vaccine such as:
    • Hives
    • Throat and/or tongue swelling
    • Difficulty breathing or shock
  • Has a severe allergy to any part of the vaccine except egg
  • Has a new or worsening illness, with or without fever (however, if you have a cold or other minor illness, you can still be immunized)
  • Has had Guillain-Barré Syndrome within 6 weeks of a past influenza vaccine
  • Has had Oculorespiratory syndrome with lower respiratory symptoms
  • Is under 6 months of age

If you fall into any of the above categories, depending on the situation, you might need to speak with your physician, or return after an appropriate time interval.

Get the flu shot every year

The best time to get the vaccine is between October and mid-November each year. It is recommended to receive the vaccine before influenza reaches the community but it can be given even after there is influenza activity. It is also recommended for travellers to destinations where influenza is likely to be circulating.

  • Adults: 1 dose of vaccine per year
  • Children under 9 years old (who have never been immunized):
    • 2 doses of vaccine given at least 4 weeks apart
    • Then 1 dose per year thereafter

When to seek medical attention

As with other vaccines, you should stay for at least 15 minutes after receiving your immunization. You should seek medical attention if you experience the following:

  • Swelling of the lips, tongue or face
  • Trouble breathing
  • Hives
  • Convulsions
  • Dizziness
  • Lasting or worsening weakness
  • High fever (40°C or 104°F)

Contact your family doctor or go to the nearest emergency room right away if you have any of these symptoms within 3 days of getting the influenza vaccine.

To get your free flu immunization, visit:

  • Your doctor
  • A local pharmacy*
  • A walk-in clinic

*Children under 5 years of age must visit their doctor. Looking for a family doctor? We can help.