Do we know how many Americans have been exposed to the virus? Is there any way to tell? It seems that current testing only reveals if one is "infected" at the time of the test. Does a negative result mean that someone has not been exposed to the virus? What if a large portion of the population already has been exposed? Are they still in danger? What caused the 1918 Flu epidemic to end? Will the same thing happen to Covid-19? Any thoughts?