Antibody testing, also known as serologic testing, is used to detect antibodies in a patient’s blood specimen (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. Serologic tests detect antibodies against infectious agents in serum and are a marker of an immune response to infection. IgG antibodies to SARS-CoV-2 develop approximately 8 to 11 days post-symptom onset (seroconversion) for the majority of patients.
Some individuals may develop antibodies after this time frame, while others, particularly those who are immunosuppressed, may never develop a detectable immune response. We are offering serology testing only as a means to detect antibodies to the virus, not to diagnose recent or active infection. Symptomatic patients should be tested using PCR viral testing, not antibody serology testing.