The flu is a very common illness, and it is likely that your child will be exposed to it several times in his or her life, if not every year. Fortunately, this illness is rarely life-threatening in children, but it can lead to hospitalization in certain circumstances. The side effects are usually mild. We recommend this vaccine mainly because influenza is so common. Not only will it help your child when he or she is exposed, but it will also help prevent the spread of the illness to others who are at higher risk of complications.