About the flu shot


The "flu shot" is an annual immunization against three strains of the influenza (flu) viruses expected to circulate for that year.

The flu shot is safe and it's the most effective way to protect yourself and your family from the flu.

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Read transcript for: You and the Flu 100kb [PDF]

Getting the shot

How does the flu shot work?

The flu shot works by prompting your body to build its natural immunity. Here's how:

  • You get the flu shot, which contains inactive (dead) flu viruses.
  • When your body comes into contact with the flu - even though the strains are inactive, you make antibodies that fight those viruses—even though they are inactive.
  • You're now ready to fight off those flu viruses, using your own natural antibodies.

Basically the flu shot, and all vaccinations, help your body build natural immunities by triggering a natural response from your immune system.

Should I get the seasonal flu shot?

YES, because:

  • Getting a flu shot is the best protection against getting the flu. Studies have found that the flu shot can prevent 60 to 80%* of influenza in healthy adults and children.
  • It reduces the risk of serious flu complications. An Ontario study** showed that every year, the flu shot eliminates 30,000 visits to hospital emergency departments. It also prevents approximately 300 deaths.
  • It's free. Ontario is one of very few places in the world that offer free flu vaccine every year to its residents.

The flu shot is recommended for everyone over six months of age.

The following people are at greatest risk from the flu — and are strongly encouraged to get the flu shot:

  • people with weakened immune systems
  • young children six months to 59 months of age
  • the elderly
  • pregnant women
  • family members and those who provide care to people in the groups listed above should also get the flu shot to protect themselves and those around them.

*National Advisory Committee on Immunization (NACI), Statement on Seasonal Trivalent Inactivated Influenza Vaccine (TIV) 2010-2011 ** Kwong JC, et al. 2008

How well does the flu shot protect against the flu?

When there is a good match between the seasonal flu types in the vaccine and the flu types circulating in the community, the flu shot can prevent the flu in about 60% to 80% of healthy children and adults.

For the elderly, studies have shown that flu shots decrease the incidence of:

  • pneumonia
  • hospital admission
  • death

The flu shot also reduces physician visits, hospitalization and death in high-risk persons less than 65 years of age .

It takes about two weeks after the immunization to develop protection against the flu; protection may last up to one year. People who receive the vaccine can still get the flu, but if they do, it is usually milder.

However, the flu shot will not protect against colds and other respiratory illnesses that may be mistaken for the flu but are not caused by the influenza virus.

When should I get the flu shot?

As soon as possible. It takes about two weeks for your body to develop protection. The earlier you get it, the sooner you're protected. Flu activity starts in the fall and typically continues until April. The flu shot is available throughout the season.

How many doses of the flu shot do I need?

One every year. Because the flu virus can change every year, you need protection against the types that circulate each year.

Children under 9 years of age who have never had the flu shot require two doses of flu vaccine at least one month apart.

Do I have to pay for the flu shot?

No. Flu shots are available free of charge to all Ontarians over the age of six months, who live, work or study in Ontario.

The seasonal flu shot is available in physician offices and through flu clinics which may be offered by:

  • public health units
  • community health centres
  • community care access centres
  • public hospitals
  • long-term care homes
  • pharmacies
  • workplace clinics

Find a flu clinic near you.

How can I keep track of my flu shots and other vaccinations?

Use your Yellow Immunization Card. After you receive your flu shot, ask the doctor or nurse who administered it for a written record of your immunization on your Yellow Card. If you can’t find your Yellow Card, you can ask for a new one. Keep it in a safe place!

Whom should I talk to if I have any questions about the flu or any other vaccines?

If you have questions about the vaccine that are specific to your medical condition, you should ask your doctor or call your local public health unit.

Questions and concerns

Can the flu shot cause the flu?

No. The vaccine does not contain live viruses so you cannot get the flu from the flu shot.

What are the risks of the flu shot?

The flu shot, like any medicine, is capable of causing side effects. The risk of the vaccine causing serious harm is extremely small.

Most people who get the vaccine have either no side effects or mild side effects at the injection site such as:

  • soreness
  • redness
  • swelling

Life-threatening allergic reactions are very rare. If they do occur, it is usually within a few minutes to a few hours after receiving the vaccine. Stay at the clinic for 20 minutes after getting your shot, just to be sure. Health care providers at the clinic are trained to monitor and treat these possible reactions.

If you do have a reaction to the flu shot, report it immediately to your health care provider.

What is Guillain-Barré Syndrome (or GBS)?

GBS is a not a very common disease, it causes muscle paralysis and has been associated with certain infectious diseases. The risk of getting GBS from the flu is higher than getting GBS from the flu shot.

Overall, the risk of GBS occurring in association with immunization is small. In comparison to the small risk of GBS, the risk of illness and death associated with influenza is much greater.

For More Information
For information about flu

Call the ServiceOntario INFOline at 1-877-844-1944
TTY 1-800-387-5559
TTY (Toronto) 416-327-4282
Hours of operation : 8:30am - 5:00pm

To speak with a registered nurse

Visit Telehealth Ontario or call 1-866-797-0000
TTY: 1-866-797-0007
Hours of operation : 24 hours, 7 days a week

To find health care options in your community

Visit ontario.ca/healthcareoptions or call 1-866-330-6206.

To find a health care provider

If you don’t have a health care provider, you can register for the Health Care Connect program. Visit ontario.ca/healthcareconnect or call 1-800-445-1822.