I had tested negative at work prior to my family getting covid as far as I Knew. I did get sick for two days after Christmas however my sister recently had a cold/flu. I assumed it was from that. I then tested shortly after two were rapid tests, and three were testing sites by gov. And those were all negative. However I did 3 tests at Stanford my primary healthcare and those came positive. Timeline is  Monday (20th), Tuesday (28th), Thursday morning ( 30th), Friday ( 31st) , Wednesday (5th)  all negative. The positives were from Thursday night( 30th), Sunday (2nd),  and  Sat( 8th) which were the Stanford one. I don’t know if it’s safe to assume Stanfords would be better at detecting, but five out of 8 and three different sources would be a lot of false negatives.