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Influenza (the Flu)

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. Learn about the flu, symptoms, prevention and the flu vaccine.

Important information

  • We are currently experiencing a challenging respiratory illness season. There are several viruses circulating in our community including respiratory syncytial virus (RSV), influenza and COVID-19. The health care system is reporting an increase in severity of illness from these viruses, especially in children below 5 years of age.
  • In alignment with the Province, Halton Region Public Health is strongly recommending that residents use all layers of protection to help protect our children, families and health care system. These layers include:
    • Masking: Wear a good quality and well-fitted mask in all indoor settings including schools/child care settings, social gatherings and public settings.
    • Staying up to date with flu and COVID-19 vaccines including booster doses.
    • Screening daily for symptoms.
    • Staying home if sick.
    • Practicing good hand hygiene. Wash your hands frequently.
    • Frequently cleaning high-touch surfaces and objects.
    • Practicing physical distancing where possible.

Influenza reporting dashboard

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Stopping the spread

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

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.
  • Keep an alcohol-based hand sanitizer handy at work, home and in your car.
  • 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.
  • Do not visit long-term care and retirement homes, as well as hospitals if you have been ill or have had contact with someone who is ill. Please help protect vulnerable persons and other individuals at high risk.
  • Cough into your sleeve or a tissue and not your hands. Dispose of the tissue immediately, and wash your hands thoroughly.
  • Clean and disinfect all contaminated surfaces and frequently touched surfaces, such as doorknobs, faucet taps, light switches and toilet handles.
  • Wash your hands frequently with soap and water. Use an alcohol-based hand sanitizer when soap and water are not available.
  • Continuing to follow COVID-19 public health measures including wearing a mask, practicing hand hygiene and physical distancing will help to keep cases of flu low this year.


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 and ear infections
  • Nausea
  • Vomiting
  • Diarrhea
  • Croup

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

Most us of are at risk of infection from 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

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

Cold and Flu symptoms are similar to the symptoms of COVID-19. For more information about signs and symptoms of COVID-19 and whether you need to get tested, visit the COVID-19 (2019 Novel Coronavirus) webpage.

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.

Please note, these symptoms are subject to change. For the latest on symptoms, visit the Ontario Ministry of Health’s Guidance for the Health Sector webpage (external link).

Treatment and recovery

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

  • Drink a lot of fluid.
  • Get plenty of rest.
  • Take a pain reliever (aspirin or acetaminophen) for head and muscle aches. Children and teenagers who have the flu should avoid aspirin unless specifically directed by a physician.
  • Contact your family doctor if illness persists or becomes worse, or call Health Connect Ontario (external link) (formerly TeleHealth) by calling 811 to speak with a nurse. Health Connect Ontario (external link) also has an online chat function to speak with a nurse.

While you are sick, make sure to reduce spread to others by taking the protective steps above.

Symptoms of COVID and the flu are very similar. If you think you have COVID-19, you may be eligible for a clinical assessment or testing. Clinical Assessment Centres can assess, test, and provide treatment options for COVID-19. Visit the Province’s COVID-19 testing and treatment webpage (external link) to see who can visit a clinical assessment centre.

Currently, there is one clinical assessment centre in Halton:

Oakville COVID, Cold and Flu Clinic

A complete list of clinical assessment centres in Halton and across Ontario can be found on the Provincial website (external link).


Please read the list of frequently asked questions below about the flu, who should get it, where to go to get the shot and other information.

The flu vaccine is designed to protect against strains of the influenza virus that are expected to be circulating during 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.

The National Advisory Committee on Immunization (NACI) (external link) recommends the flu vaccine for anyone 6 months of age and older who has not had an adverse reaction to the vaccine. It is especially recommended for persons:

  • at high risk of severe disease, flu-related complications or hospitalization;
  • capable of transmitting the flu to those at high risk;
  • who provide essential community services; and
  • in direct contact with poultry infected with avian influenza during culling operations.

Individuals who should not get the flu vaccine include anyone who:

  • has had severe allergic reaction within 24 hours of receiving an flu vaccine such as:
    • wheezing
    • chest tightness
    • difficulty breathing
  • has had a significant allergic reaction to any component of the vaccine except for egg;
  • has had Guillain-Barré Syndrome within 6 weeks of a past influenza vaccine;
  • is under 6 months of age.

Consult with your Health Care Provider if you meet these criteria to determine if the flu vaccine is right for you.

Individuals with a COVID-19 infection should not leave isolation solely to receive the flu vaccine. This is to reduce the risk of spreading COVID-19 to others. Individuals who have a different or unknown new/worsening mild-to-moderate illness can safely be vaccinated against the flu. However, the current recommendation is for medical visits to be delayed until the illness is resolved, to reduce risk of spreading COVID-19 or other illnesses.

To get your free flu immunization, book an appointment with:

  • your doctor
  • a local pharmacy*
  • a walk-in clinic

*Children under 2 years of age must visit their doctor. Looking for a family doctor? We can help.

Participating pharmacies are offering both the high-dose and regular flu vaccines. Find the closest participating pharmacy in:

Residents can also sign up to be notified when and where flu shots become available by visiting

Keep a record of your flu vaccination

  • After you get your immunization, you will be given a written record. Add this information to your immunization record.
  • If you received the vaccine at a pharmacy, share this information with your regular health care provider. 
  • If you develop respiratory symptoms over the next few months, this information will be an important part of your care plan.

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 one to two days after vaccination, include soreness, 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), 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 may safely have the flu vaccine but should talk to their health care provider before being immunized.

When do I seek medical attention?

As with other vaccines, you should stay on site in the health care provider’s office (or pharmacy) 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.

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 two weeks to build up protection to the flu virus after you receive immunization; protection might last up to one year.

High dose quadrivalent vaccine (QIV-HD) and adjuvanted trivalent vaccine (TIV-adj) is authorized only for persons 65 years of age and older.

However, the Standard dose Quadrivalent (QIV), High dose quadrivalent vaccine (QIV-HD) and adjuvanted trivalent vaccine (TIV-adj) ALL protect against the flu, and the most important thing is for seniors to be vaccinated as soon as the flu vaccine is made available. Do not delay vaccination to wait for a particular product.

FluMist® (intranasal spray) is not available this year through the publicly funded flu program but may be available for purchase. Please contact your pharmacy/physician for more information.

Flu shots are now available to all Ontarians six months of age and older. You should get a flu shot as soon as possible because the body needs two weeks to build up protection to the flu virus after you receive immunization.

  • The Ministry of Health orders the vaccine for the province of Ontario.
  • The vaccine arrives at the Ministry’s central pharmacy in multiple shipments over a period of two to three months. Typically, the first shipments of flu vaccine arrive by the beginning of October.
  • As the shipments come in, each Public Health Unit and pharmacy distributor receives a portion of those shipments.
  • Public Health Units then send vaccine out to local health care providers. Pharmacy distributors send the flu vaccine out to the pharmacies.
Product Availability Vaccine Product Age Indication
Quadrivalent Inactivated Vaccine (QIV)
  • FluLaval® Tetra
  • Fluzone® Quadrivalent
≥6 months
  • Afluria® Tetra (supplied to Pharmacies Only)
≥5 years
High-Dose Quadrivalent Inactivated Vaccine (QIV-HD)
  • Fluzone® High-Dose Quadrivalent
≥65 years
Adjuvanted Trivalent Inactivated Vaccine (TIV-adj)
  • Fluad®
≥65 years

High dose quadrivalent vaccine (QIV-HD) and adjuvanted trivalent vaccine (TIV-adj) is authorized onlyfor persons 65 years of age and older.

ALL age appropriate flu vaccine protect against the flu. Do not delay vaccination to wait for a particular product.

Flu vaccines do not provide protection against COVID-19 virus. Individuals are encouraged to receive their annual flu shot and any recommended COVID-19 booster doses. Visit to learn where you can get your COVID-19 vaccine and recommendations.

All available flu vaccines can be given at the same time as other vaccines, or at any time before or after vaccines, including COVID-19 vaccines for individuals 6 months of age and older.