Fluorescent Immunoassay for Anti-SARS-CoV-2 Nucleocapsid Antibodies (Serum/Plasma)
This test detects antibodies in your blood that your immune system produces in response to the SARS-CoV-2 virus, which causes COVID-19. It helps determine if you’ve been exposed to the virus and whether your body has mounted an immune response.
["Assists in assessing past infection and immune response to COVID-19."]
Key facts at a glance
- LOINC
- 88835-4
- Short code
- FLUAV swine RNA Ct Spec Qn NAA+probe
- Synonyms
- FLUAV swine RNA Ct Spec Qn NAA+probe
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- probe-amp-tar
- 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
Why This Test Matters
While a positive result suggests your immune system has recognized the virus, it does not confirm a recent infection. Antibodies may take days to weeks to develop after exposure. This test is often used alongside other diagnostic tools to guide decisions about vaccination, exposure risk, or ongoing monitoring.
How the Test Works
The test uses a fluorescent immunoassay to detect specific antibodies (IgG) against the SARS-CoV-2 nucleocapsid protein. A small sample of your serum or plasma is mixed with labeled antibodies that bind to the target protein if present. Fluorescence signals indicate a positive result, meaning your body has likely encountered the virus.
Sample Collection
A blood sample is drawn from a vein in your arm. The sample is processed into serum or plasma for testing. This is a quick procedure, typically done at a clinic or lab, and you may feel a brief pinch or slight discomfort.
What to Expect Before or After
Before the test: No special preparation is needed, but inform your provider if you’re on blood-thinning medications or have a history of bleeding disorders. After the test: Mild bruising or soreness at the injection site may occur. Rest and monitor the area for signs of infection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
COVID-19 Antibody Test (Nucleocapsid)
Frequently asked questions
This test helps identify whether you’ve had an infection with SARS-CoV-2, even if you didn’t experience symptoms. Antibody levels can vary over time—positive results may fade as immunity wanes. It’s useful for tracking immune response after vaccination or recovery, but it’s not a substitute for viral testing (e.g., PCR or rapid antigen tests) to confirm active infection.
Can this test show if I have active COVID-19?
How long after infection do antibodies appear?
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