The best time to get a flu shot is generally in September or October before the flu season starts, as it takes about two weeks for the body to build immunity. For most people in the northern hemisphere, flu season usually begins in October and peaks between December and February. Getting vaccinated by the end of October offers optimal protection during the highest risk period. However, if this window is missed, it is still beneficial to get vaccinated later in the season as flu activity can continue into spring. Some exceptions include:
- Pregnant women can get vaccinated from September, with those in the third trimester sometimes advised to get vaccinated earlier for baby's protection.
- Children who require two doses should start as soon as the vaccine is available (sometimes as early as August or September).
- People over 65 should get a flu shot preferably in September or October, often with a high-dose vaccine.
Overall, receiving the flu shot in early fall (September or October) is recommended to best balance early immunity with lasting protection through the flu season.
