You never know. My kids have been taking flu shots every years since 4 years ago. This year is the first time my elder is suspected to have flu (i.e may or may not be, and did not even tested) because no matter it is or not, as long as the kids are not having serious fever, they just treat it as ordinary virus. Our doctor said she doesn't need to take the flu antibiotics because her symtom is mild due to probably she previously took a flu shot which prevents her from developing into serious symptoms.
My doctor recommends children to take shot, same as our gov't, because the chance for developing into fatal complication is 1/10,000 (not sure if I remember it correctly) which is considered high, i.e. among 500,000, there would be 20+ death due to complication. The worst thing about flu is the complication which leads to death.