I have a question for any epidemiologists and virologists who might be reading this: What if SARS-CoV-2 is no different from other coronaviruses? What if this is just what coronaviruses do, and we've only just now noticed because we have an entirely unexposed population?
What if coronaviruses usually cause severe illness in the old and mild illness in the very young? What if most people are first exposed when young so that they usually have a mild case? What if the brain fog, inflammation, cardiovascular issues, and other lingering effects that we see in an alarming proportion of young adults are something that has been happening all along with other coronaviruses? (When someone comes to a doctor complaining of brain fog, no one ever suspects the cold they had a couple weeks ago.) If this were true, we might never notice, because there's only so much funding for studying the common cold. It would be difficult to make an epidemiological study with such a huge proportion of the population already long since exposed. It would only become evident in a pandemic situation.
I don't have the background to know how to evaluate this idea. But I'm a little concerned that no one can answer it—that perhaps coronaviruses are poorly studied enough that we can't even rule out this speculation.