Kids also have smaller anatomies, so when they get sick, they don’t know how to expectorate mucus, for example, like adults do.”Witthaya Prasongsin // Getty ImagesWhy is a flu shot important for your childBecause flu viruses change, everyone ages 6 months and older needs a flu shot every year. Witthaya Prasongsin // Getty ImagesWhen is the best time for your child to get a flu shot? Typically, flu season runs from October to May, so the best time to get a flu shot is in the fall. Karl Tapales // Getty ImagesDoes your child need two doses of the flu shot? However, if they receive a flu shot later in the season it can still be protective.