looking at officially recorded data only, in England only;
there are 1,288,186 covid cases < 30 yrs.
there are 231 covid deaths < 30 yrs
this means the IFR on known cases is ~0.018 %
known cases is surely nowhere near the real cases, especially in the younger population. I would bet it's double at the very least.
a 'positive' that predominantly younger folks are getting it is that it translates into far less deaths further down the line, with zero vaccination.
(upping that to < 40 yrs = 0.04%. Again only recorded cases, which will be a large under estimate.)