Serum or Plasma Anti-SARS-CoV-2 Nucleocapsid Antibody, Immunoassay
This test measures 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 developed immunity.
["This test checks for past infection by detecting antibodies to a key viral protein."]
Key facts at a glance
- LOINC
- 5356-1
- Short code
- ENA SM Ab Ser Ql IA
- Synonyms
- ENA SM Ab Ser Ql IA
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- 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 Might Be Ordered
Your healthcare provider may recommend this test if you’ve had symptoms of COVID-19, recovered from it, or been exposed to someone with the virus. It can also be used to assess immunity after vaccination or to monitor long-term immune response in certain situations.
What to Expect Before the Test
No special preparation is needed. You may have a simple blood draw from a vein in your arm. The test uses a small amount of your blood to detect antibodies in your serum or plasma.
What the Test Results Mean
Positive results indicate the presence of antibodies against the virus’s nucleocapsid protein, suggesting prior infection. Negative results mean no detectable antibodies, which could mean you haven’t been infected recently or your immune response hasn’t produced these antibodies yet.
Common Reasons for Testing
This test is often used to confirm past COVID-19 infection, evaluate vaccine-induced immunity, or screen for asymptomatic carriers in certain settings.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: This test helps distinguish between active infection (detected by viral testing) and past infection, which is important for understanding immunity and guiding public health or vaccination strategies. It’s not a diagnostic tool for current illness but can inform long-term health monitoring.
Short name
Anti-Nucleocapsid Antibody
Frequently asked questions
Can this test detect COVID-19 if I’m currently sick?
How long after infection can I expect to see positive results?
Does this test replace a viral test for diagnosing COVID-19?
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