Or the reverse, tests returning to negative before symptoms kick in: the tests only check for presence in the accessible part of the throat and that area is kno

Or the reverse, tests returning to negative before symptoms kick in: the tests only check for presence in the accessible part of the throat and that area is known to get negative after a few days (apparently the virus is easy to defeat there). An infection down in the lungs could still be in early stages and growing at that time so symptoms would later appear as if out of a (recently clearedh clear sky.