Antibody tests have an important role in COVID-19 diagnostics although they are not the first tool for a patient presenting with recent start of the illness. Patients who come to the physician after having symptoms present for more than nine days, benefit from serological tests since the sensitivity of direct virus detection is decreasing due to the decreasing number of viruses. Instead, the sensitivity of serological tests increases over time. The serological tests can be offered for these patients in addition to direct detection methods.
Lengthy symptoms are common in adults who have had COVID-19 illness. Antibody tests are a useful means for the physician to determine if a patient with symptoms has had an earlier non-diagnosed COVID-19 illness.