Many years ago I had a friend who died in his early twenties, falling out a window. An autopsy found that he had a previously undetected heart condition and had had a heart attack and fallen. I don't think the CT scan technology that would have shown the defect even existed at the time. In any event, he was a healthy young man and there was no reason to think he might have had a heart defect.
We know that among the possible long-term consequences of covid are lung damage, heart damage, and kidney damage. I wonder how many of those schoolchildren who are infected with covid are going to develop unforeseen lethal or severely disabling conditions in their twenties.
This is, of course, speculation. I think it very likely that many children will grow up and turn out to have long-term consequences of covid, but I don't know that it will actually happen. But neither do the leaders who are allowing the unchecked spread of covid among children.