Serum/Plasma Immunoassay for Antibodies to SARS-CoV-2 (Nucleocapsid Protein)
This test measures antibodies in your blood that your immune system produces in response to the SARS-CoV-2 virus, which causes COVID-19. Antibodies can help your body recognize and fight the virus if you become infected again.
This test helps track your immune response to COVID-19 over time.
Key facts at a glance
- LOINC
- 97145-7
- Short code
- HELPFULCOPINGSTRATEGYYOURCHILDUSEDDURINGTHECOVID19OUTBREAK
- Synonyms
- —
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 3.5
- Ref high
- 5
- Critical range
- 2.5 N/A – 6.5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84132
- SNOMED
- 110742001
- 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 This Test Measures
The test detects antibodies specifically targeting the nucleocapsid protein of SARS-CoV-2. These antibodies are part of your immune system’s defense and appear after infection or vaccination. The presence of these antibodies suggests your body has recognized and responded to the virus.
Why It Matters for Your Health
While antibodies don’t guarantee immunity or protect against future infections, they indicate your immune system’s activity in response to COVID-19. This information can be useful for monitoring recovery, understanding past exposure, or assessing immune response to vaccination.
How the Test Works
The test uses a blood sample (serum or plasma) to identify antibodies through an immunoassay method. This involves detecting the presence of antibodies that bind to the nucleocapsid protein of the virus, confirming exposure or immune activation.
When You Might Need This Test
Your healthcare provider may recommend this test if you’ve had COVID-19 symptoms, suspect past exposure, or are evaluating your immune response after vaccination. It’s also sometimes used in research or surveillance studies.
Reference range
Adult: 3.5-5.0 mmol/LN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Antibody levels can vary over time—some people develop strong responses quickly, while others may take longer. High antibody levels may suggest a robust immune reaction, but they don’t always mean you’re immune to future infections. This test is often used alongside other diagnostic tools for context.
Short name
COVID-19 Antibody Test (Nucleocapsid)
Frequently asked questions
How long does it take to develop detectable antibodies after COVID-19 infection?
Can this test tell me if I’m currently infected with COVID-19?
Are antibody levels the same for everyone after vaccination?
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