Yeah, the flu is mostly dangerous to juniors and seniors. Juniors, because they haven't developed the immunity system fully yet... seniors, because their immunity system is having an Alzheimers or something.
But if your kids are healthy, you've got nothing to fear. I'd worry about kids whose moms kept them waaaaay too sterile. Don't say no when kids want to play in the dirt - it makes 'em into excellent candidates for Fallout-esque survival!
As long as they don't dig a landmine up, like it happened to one of kids I read about... eek. Luckily it didn't go off even as the toddler was hitting it with a toy truck. Imagine the father's face.