IgG Anti-Coronavirus Nucleocapsid Antibody (Serum) - Confirmatory
This test measures the presence of antibodies against the nucleocapsid protein of a coronavirus in your blood, confirming past infection.
["This test helps determine if you’ve had an infection with a coronavirus, such as SARS-CoV-2, by detecting immune system responses."]
Key facts at a glance
- LOINC
- 7832-9
- Short code
- COX2IGM
- Synonyms
- C burnet Ph2 IgM Ser-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube
- Units
- N/A
- Ref low
- 2
- Ref high
- 3
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunofluorescence assay (IFA)
- CPT
- 86638
- SNOMED
- 122512009
- Specimen volume
- 1-2 mL serum (minimum 0.5 mL)
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 48–168 hours
- Order
- routine
What Does This Test Measure?
The test detects IgG antibodies specific to the nucleocapsid protein of the virus. IgG antibodies are part of your immune system’s long-term response to infection. If present, they suggest your body has recognized and fought off the virus at some point.
Why Might You Need This Test?
This test may be used to confirm past infection with a coronavirus, especially if you’ve had symptoms like fever, cough, or shortness of breath, or if you’ve been exposed to someone with the virus. It can also help monitor immune responses in certain clinical settings.
How Is the Test Performed?
A blood sample is taken from a vein in your arm. The serum portion of your blood is then tested for IgG antibodies using a confirmatory immunoassay method.
What Are the Possible Results?
A positive result indicates the presence of IgG antibodies against the nucleocapsid protein, suggesting past infection. A negative result means no detectable antibodies were found, which may indicate no prior infection or insufficient immune response to detect.
Reference range
Negative: <1:16 (Phase 2 IgM antibodies not detected). Phase 2 IgM antibodies appear in the first 2-3 weeks of acute Q fever infection and typically decline within 12-16 weeks. A titer of ≥1:50 is considered presumptive evidence of recent acute infection.N/A
No fasting required. Sample should be collected prior to antibiotic administration when possible to avoid false-negative results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Anti-N Antibody (Confirm)
Frequently asked questions
What does a positive result mean?
What does a negative result mean?
How long do IgG antibodies last?
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 15, 2026. · Read our editorial policy