How long is the flu shot effective? 3 months? 6 months?...

Question: 

How long is the flu shot effective? 3 months? 6 months?

Answer: 

It is difficult to say exactly how long the flu vaccine is effective.  There are several factors including age and health of recipient and their previous exposure to flu that will affect how well they develop antibodies after being immunized. According to the Canadian Immunization Guide, annual vaccination is required because the body’s immune response from vaccination diminishes "within a year". Also, because influenza viruses change often, the specific strains in the vaccine are reviewed each year by WHO and updated as necessary so that there is the greatest probability of matching circulating viruses. If you have further questions, please contact your immunization provider.

Immunization Nurse