What is an antibody test?
An antibody test reveals if a person has already been exposed to an infection, by detecting antibodies in their blood or serum. This can be done by a laboratory-based test such as an ELISA (enzyme-linked immunosorbent assay) or CIA (chemiluminescent immunoassay), or a point-of-care test based on lateral flow technology.
Antibody tests are not usually used to diagnose current infection as it takes the body some time to produce antibodies. During the period before the adaptive immune system kicks in, the fast-acting and non-specific innate immune response combats infection.
Data suggests that in the case of SARS-CoV-2, the IgM antibody response peaks around two weeks after infection, followed by the IgG antibody peak at three weeks.