Is the Seasonal Flu Vaccine Effective?

Yes. Getting the flu vaccine every year is your best defense against fighting influenza (the flu). Every year, the World Health Organization monitors the global spread of flu and identifies which flu strains will likely cause the most illness during flu season. Those strains are then used to create the flu vaccine for that upcoming flu season. Because the strains can change every year, the vaccine can be different each year. It is important to get the flu vaccine every year because the viruses change from year-to-year and the protection provided by the vaccine decreases over time.

Canada, the United States, and the United Kingdom are some of the countries that measure how well the flu vaccine protects against influenza-related illnesses each year. While flu vaccine effectiveness varies each year, the flu vaccine has been shown to be efficacious, with higher efficacy demonstrated against laboratory-confirmed influenza than clinically defined outcomes. Additionally, immunization has been shown to reduce the number of physician visits, hospitalizations and deaths in high-risk adults. Being immunized against the flu provides better protection than not getting immunized at all.

Flu vaccine effectiveness can vary from year to year. Characteristics of the person being immunized, such as their age and health status, may affect how well the vaccine works. The similarity or “match” between the flu viruses the vaccine is designed to protect against and the flu viruses circulating in the community, may also affect flu vaccine effectiveness. Additionally, the type of flu vaccine administered may influence vaccine effectiveness. Manitoba Health offers a high-dose inactivated influenza vaccine to people aged 65 years and older who are living in congregate settings and/or who have difficulty accessing health care services based on where they live. It is expected to elicit a stronger, more effective immune response among elderly individuals who are at higher risk of complications from the flu compared to younger populations. Evidence suggests that this population does not develop optimal protection with the standard-dose influenza vaccine.

The contents of this webpage has been adapted from the Centers for Disease Control and Prevention (

If you have any questions about seasonal flu or pneumococcal immunization:

Speak with a health care provider or call Health Links – Info Santé at:

204-788-8200 in Winnipeg or toll-free 1-888-315-9257