It is a clear cut answer if you understand what an mRNA vaccine is.
BTW the "long tail" of COVID-19 in children is totally unproven and the whole "long haulers" phenomenom is likely (a) a small part normal post-viral fatigue which we see with basically any virus, and (b) mostly psychosomatic/psychogenic illness.
So when faced with the choice of vaccine or virus, it should be a foregone conclusion.