I don't have the age breakdown but serious/long Covid is about 15% of cases, which is potentially millions of people in most countries if we let the epidemic rip through. Symptoms include mental fog, loss of concentration, extreme fatigue, loss of smell..

This is why the idea of chasing herd immunity without a vaccine has always been misguided

You seem to be combining “serious” and “long” cases together. We already know that the vast majority of “serious” cases occur in the elderly/sickly, so your statistic of 15% is useless FUD.