I think the FDA is late to acknowledge this.
People have been vaccinating kids in Europe for quite a while. That's one reason the take-up rates are so high.
On the other hand, if I had a healthy child in this age range, I'd definitely be wondering whether I thought the risks and benefits worked for my child. Because the FDA are bound to be thinking about the benefits to society as a whole and where a small child is concerned, you'd probably think, to hell with society. There's close to zero risk for a healthy child.
If I had an unhealthy child, I'd be screaming with joy.