Anti-SARS-CoV-2 Immunoglobulin G (IgG) Antibody Test (Serum/Plasma)
This test measures the presence of Immunoglobulin G (IgG) antibodies in your blood against the virus that causes COVID-19. IgG antibodies are part of your immune system’s long-term defense and can indicate past infection or vaccination.
IgG antibodies help your body remember the virus for future protection.
Key facts at a glance
- LOINC
- 98173-8
- Short code
- REASONSFORNOTACCEPTINGCOVID19VACCINE
- Synonyms
- —
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85610
- SNOMED
- 396252006
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Does This Test Measure?
IgG antibodies are a type of antibody produced by your immune system in response to exposure to the COVID-19 virus. They are typically detected weeks to months after infection or vaccination. This test helps determine if your body has developed immunity through either natural infection or vaccination.
Why Might You Need This Test?
Doctors may order this test to assess immunity status, especially after vaccination, to monitor recovery from COVID-19, or to guide decisions about exposure risks. It can also help confirm if prior infection has led to lasting immunity.
How Is the Test Performed?
A blood sample is collected from a vein in your arm. The sample is then sent to a lab for analysis using an immunoassay method, which detects the presence of IgG antibodies specific to the COVID-19 virus.
What Do the Results Mean?
Positive results indicate the presence of IgG antibodies, suggesting your body has developed immunity. Negative results mean no detectable IgG antibodies were found at the time of testing, though this does not rule out past infection or early immune response.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: IgG Antibodies and COVID-19 Immunity
Short name
IgG Antibody to COVID-19
Frequently asked questions
IgG antibodies play a key role in long-term immunity against COVID-19. While they do not provide immediate protection like antibodies from recent infection or vaccination, they contribute to sustained defense. Levels can vary over time and may decline gradually, so regular monitoring may be recommended in certain situations.
What if I Had COVID-19 Recently?
Can This Test Be Used to Determine Vaccine Effectiveness?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy