My wife’s a nurse and had major surgery last year putting her on the edge of the most at risk group. She was tolls to stay at home at the outset and was quite ill, she quarantined herself from the rest of us for 2 weeks and my sons both self isolated from work (I’m retired). Everyone including medical staff/friends were convinced she had it but as she was away from work didn’t get a test. After bout 10 weeks she was given the ok to return to work dependent on a negative test. To everyone’s surprise it came back as her not having had it, actually made her a tad disappointed in a strange way as having gone brought everything you almost want to find you have the anti body. Of course there is also the chance that the tests aren’t fully accurate.