The FDA themselves today said that this was a concern that the trial was not able to effectively address due to its small sample size. They said it is a concern that warrants further monitoring. These are their caveats to the emergency use authorization, not mine.
I am not saying that the vaccine is unsafe. I personally have had two doses of Moderna myself and I believe in it. However, I have concerns specifically around the clinical trial for this age group, how relatively small it was, and how even the FDA is saying there still needs to be more monitoring and more data collected. I don't think that is unreasonable, nor is it fringe anti-vax propaganda, given what the FDA itself has said. I think the trial should have been conducted with a larger group of children.