It’s flu season again and the flu shot is here! But why is it so important to get this yearly vaccine and how does it work?

Influenza, or the flu, is a virus that can make its way into your lungs with one simple breath. From there, the flu can invade your lung cells (called an infection) and start making copies of itself. These infected cells stop functioning properly, and this activates your immune system (the body’s army against invaders) to target the lungs and try to get rid of the virus.

Did You Know?
In Canada, the flu season usually runs from November to April.

The flu shot, or vaccine, contains flu viruses that have been killed. Some people worry that if they get the flu shot, they will get the flu. This isn’t true! In order for you to get sick from the flu, the flu virus has to be alive. So, if the virus is dead, or inactivated, it can’t attack your cells to start an infection. Instead, it acts like a warning sign for the immune system, showing it what the virus looks like. A vaccine is just like those “WANTED” posters you see in old Western films. With this warning, the body is able to kick the flu out before it gets a chance to make you sick.

Did You Know?
The war between the flu virus and your immune system is what makes you feel sick.

So, if your body’s army knows what the flu looks like, why do you have to get a flu shot every year? Each season the flu virus changes its appearance—just like a criminal growing a moustache or dying his hair. This means the picture on your "WANTED" poster needs to be updated to keep you safe!

Did You Know?
A cold is caused by a rhinovirus, which is not the same as the influenza "flu" virus.

By getting a flu shot you’re not only protecting yourself but also protecting your classmates and grandparents, whose immune systems may not be as strong as yours.

Want to know how else you can you protect yourself from the flu? It’s simple: WASH YOUR HANDS! This helps prevent the spread of infection through objects like door handles and keyboards. If you have questions, talk to a doctor or the school nurse for more information.

Learn More!

Influenza (Seasonal Flu) and the Influenza Vaccine

Flu Shots - Help slow down the spread of influenza


Fiore AE, Bridges CB and Cox NJ (2009). Seasonal Influenza Vaccines. InCompans RW & Orenstein WA (Eds.), Current topics in microbiology and immunology: Vaccines for Pandemic Influenza (pp. 43-82). New York: Springer.

Article first published December 15, 2011

Elisa Porfilio

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