Would we have observed anything unusual?
I'm not sure we would have.
Consider
(1) Our kid got pretty sick right when news of COVID was breaking. We talked to the doctors office and was told the same old routine - monitor for fever and breathing and otherwise have the kid rest and drink fluids. He got better in a couple of days although he had a cough for a few days afterwards.
(2) SIL is a school teacher. She got a bad cold and right about the time schools were closed she took days off. She never tested positive but she would have been out of school for at least two weeks with whatever she did have.