My DH tested positive for covid yesterday morning after feeling rubbish for a few hours. There was a definite line. He had tested negative the previous day. (He had tested because he was seeing elderly parents) That afternoon he tested again, but it was negative. This morning he tested positive, but only very faintly. It looks like he may only be positive for 2 days. I haven't heard of this happening to anyone else. Have you? Two of my DC's were pretty much asymptomatic but still tested positive for 8 or 9 days.