Antibody Testing (Ab)
Antibody testing is also known as serologic testing. It is used to detect antibodies in the blood specimen or serum. Antibodies are produced by the immune system in response to an infection. The presence of antibodies indicates that an individual has been exposed to (infected with) that particular infectious agent. These antibodies can be detected in some cases for years after the individual has recovered from the infection and will also be present if the patient was never even symptomatic.
IgG antibodies to SARS-CoV-2 (COVID-19) usually develop 8-11 days post-symptom onset. Some individuals can develop antibodies after this time frame, while others may never develop a detectable immune response.
Detection can indicate prior exposure (infection) to the virus and the presence of an immune response that suggests the patient is less likely to get infected or re-infected compared to seronegative individuals.