SARS-CoV-2 Serology (COVID-19) Antibody FAQ

What is an antibody test?

An antibody test is a blood test to see if you have been exposed to the COVID-19 virus. These antibodies typically appear around two weeks after exposure to the virus (or 7-10 days from the onset of symptoms such as fever or cough).

What does an antibody test do?

If COVID-19 antibodies are detected, it does not mean that you are immune to the virus. However, the presence of antibodies can help develop a more accurate case count for the region as well as developing any patterns for patients who have the virus in their systems but are asymptomatic.

How much does an antibody test cost?

Our antibody test has a $25 blood draw fee. If you have insurance, the blood draw fee is your only out of pocket expense. Otherwise, if you do not have insurance, you will need to pay the remaining $50 out of pocket.

What do my results of (COVID-19) Antibody (IgG), Immunoassay mean?

Results from this qualitative test for SARS CoV-2 IgG can be positive (reactive), negative (non-reactive), or, occasionally, equivocal (borderline).

A positive (reactive) result indicates detection of COVID-19 IgG, which may suggest exposure to COVID-19. It usually takes at least 10 days after symptom onset for IgG to reach detectable levels. Although the relationship between IgG positivity and immunity to COVID-19 has not yet been established, the detection of IgG antibodies may suggest an immune response to COVID-19 after resolution of infection with COVID-19. Antibody tests should not be used to diagnose COVID-19 infection. Patients with symptoms should be evaluated with a molecular assay instead.

A negative (non-reactive) result indicates that COVID-19 IgG is not present at a level that is detectable by the COVID-19 Antibody Immunoassay. It usually takes at least 10 days after symptom onset for IgG to reach detectable levels. However, the rate of IgG development can vary between individuals, and it is currently not known for how long IgG remains detectable after exposure to SARS-CoV-2. Negative results do not rule out COVID-19 infection, particularly in those who have been in contact with the SARS-CoV-2 virus. Follow-up testing with a molecular diagnostic assay should be considered to rule out infection if clinical condition is indicated.

An equivocal (borderline) result indicates that IgG was detected at a level or close to the threshold of the limit of detection for the test. Equivocal results may represent an early infection, detection of an IgG generated from a past infection or, in some cases, an underlying immune disorder, immunosuppression or other reasons.

Does a positive result for IgG to SARS-CoV-2 mean that the patient is immune?

Presence of IgG to COVID-19 indicates that the patient has mounted an immune response to the virus. Although the immune response may protect against reinfection, this has yet to be established. It is also not known how long antibodies to the virus will protect someone, if at all. Scientists are conducting research to answer these questions. Therefore, patients with positive IgG results should continue to take steps to protect themselves and others.