The low-down on this is that influenza often kills those who are otherwise well. Also, the flu can be fatal to children.
The CDC found that 830 kids died from flu-related complications between 2004 and 2012 and most of those had not gotten a flu vaccine. Pneumonia was the most commonly reported complication among the kids who died 43% of the kids who died from flu complications were otherwise healthy and did not have high-risk medical conditions (like heart defects, epilepsy, diabetes, cancer, or asthma).
The CDC recommends that all children 6 months or older get the flu vaccine every year. Prevention IS the best strategy. Children younger than 9 who are receiving the vaccine for the first time need two doses. If they only get one vaccine the first year of flu vaccination, it’s as though they are not vaccinated that season.