sorry, i forgot to include the fact that the illnesses i described were in march 2020, the same time-frame as yours ...
How much time passed between the illness and the antibody test?
What kind of antibody test, IgG IgM or T-cell?
Reason I ask is back in March 2020 I had shortness of breath, fatigue, loss of smell, no fever or cough, and tested negative at the urgentcare for flus and strep (no covid test was available).