Antibody tests were only widely available in July-August, so people who got COVID in Feb or March often didn't have high enough antibody counts by that point to flag positive on the tests.
The half-life of antibody levels has been estimated at 73 days. The antibody tests are quite sensitive, time has not been enough of a factor yet to produce false negatives. In a year or two it might be.
The only time concern is that you need to wait 2-3 weeks until after you recover from COVID to ensure you test positive.
The half-life of antibody levels has been estimated at 73 days. The antibody tests are quite sensitive, time has not been enough of a factor yet to produce false negatives. In a year or two it might be.
The only time concern is that you need to wait 2-3 weeks until after you recover from COVID to ensure you test positive.