What's the science behind the flu shot?

You're probably seeing signs in pharmacies and around your workplace – it's flu shot season, but what's the science behind the flu shot?

The influenza (flu) shot does not consist of a live virus, but rather non-viable components from the virus called antigens. It is impossible for the influenza shot to give you the flu.

“Because there are many different strains of the flu, each year experts reformulate the flu vaccine to include the three or four strains which are predominant that year,” says Dr. Kevin Katz, Medical Director, Infection Prevention and Control at North York General Hospital.

Dr. Kevin Katz, Medical Director, Infection Prevention and Control, North York General Hospital

Dr. Kevin Katz, Medical Director, Infection Prevention and Control

How well the flu vaccine works can vary from season to season and person to person. In general, getting the flu vaccine prevents any influenza infection about 60% of the time, while the 40% who may still become infected get a much milder form of the infection. The factors that come into play include the age and health of each person, and the match of the flu virus to the vaccine. Not getting the vaccine means you will have zero protection, so it's always recommended to get a yearly shot.

“Some protection is better than none,” explains Dr. Katz. “Receiving the flu shot is like spraying yourself with bug spray before going into the woods, it's a preventative measure. Even better, by reducing your risk of infection, it also protects others you come into contact with such as people with weakened immune systems like grandparents and small infants who may not be as protected from influenza.”

Once you receive the flu shot, it takes approximately two weeks to develop antibodies (large proteins that find and help remove viruses and bacteria) which protect you so mark it in your calendar!

NYGH President and CEO Dr. Tim Rutledge gives the flu shot to Hye Youn Kim, Team Attendant, Surgery Short Stay Unit, at the launch of the hospital’s 2016 flu campaign on Oct. 18.
North York General Hospital President and CEO Dr. Tim Rutledge gives the flu shot to Hye Youn Kim, a Team Attendant in the Surgery Short Stay Unit, at the launch of the hospital’s 2016 flu campaign on Oct. 18.


Get your flu shot at NYGH's Pharmacy


Patients and visitors can get their free flu shot at North York General's Pharmacy at the General site (4001 Leslie Street). Please bring your OHIP card.

Pharmacy hours:
Monday to Friday: 8:30 a.m. to 7 p.m.
Saturday and Sunday: 9 a.m. to 5 p.m.

Tel: 416-756-6752

This article first appeared in the November 2016 issue of The Pulse.

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