09/29/2025
How flu shots work
After receiving a flu shot, your body takes about two weeks to develop the antibodies that protect against the flu virus. It is recommended to get vaccinated by the end of October to be protected before flu season begins. However, getting the shot at any point during the flu season is still beneficial.
The flu vaccine is updated annually because flu viruses are constantly changing. This ensures the vaccine provides protection against the strains that are predicted to be most common during the upcoming season. It's a common misconception that the flu shot can give you the flu, but since it's made with an inactivated virus, it cannot cause infection.