It is not safe. Something that is safe does not kill 17,000+ people. Something that is safe does not cause healthy teenagers to suddenly have heart problems.
It is not effective. Fully vaccinated people can get covid and pass it on.
Kids are not test subjects. The trial is not over. There are no long term studies. We do not know and will not know how it will affect them
Kids are not at risk. Even if it was completely safe and effective, which it is not, the shot is meaningless.