This isn't meant to sound chippy so apologies if it does, but how many children and teens do you know?
I do think it will take a while for these numbers to come through properly. It can take a while until you realise you are still suffering. Lots of asymptomatic kids who didn't even know they had covid may now have 'mystery viruses'.
I don't think we will know for ages (if at all if ME is anything to go by).
But, anecdotally, we definitely have quite a few students just at my school who have not recovered well from covid. Of course, that will probably still be lower than 10% of those who have had it. But one is almost bedbound several months after testing positive.