How many months does a flu shot provide effective protection?

Depends: The antibody produced may last a very long time, but the particular strain of influenza encountered may have changed so that those antibodies are not effective against it. That is one reason to ensure that you receive the new vaccine yearly. It is made to protect against the most likely type of influenza to hit the community that year. Stay safe.

The season involved: Consider the flu shot you get as effective in protecting you from the strains in the vaccine for at least a year.If you get the vaccine in august, months before the regular season, you will be protected for that flu season, even if it hits in february.