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Anti-SARS-CoV-2 Nucleocapsid Protein Antibody, Serum/Plasma (Qualitative)

Published: August 9, 2026Updated: August 16, 2026

This test checks for antibodies to the nucleocapsid protein of SARS-CoV-2, the virus responsible for COVID-19. Antibodies develop after infection or vaccination and can help confirm past exposure.

Quick summary

["This test helps determine if you’ve had an infection with the virus that causes COVID-19, even if you didn’t experience symptoms."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
94762-2
Short code
SARS-CoV-2 Ab SerPl Ql IA
Synonyms
SARS-CoV-2 Ab SerPl 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

What Does This Test Measure?

The test detects antibodies (immunoglobulins) produced by your immune system in response to the nucleocapsid protein of SARS-CoV-2. These antibodies are a sign that your body has recognized and fought the virus, which may indicate past infection. Antibodies can be detected weeks to months after infection.

Why Might You Need This Test?

Healthcare providers may order this test to confirm a past COVID-19 infection in individuals who tested positive for the virus earlier or have symptoms suggestive of COVID-19 but test negative. It can also be used in research or surveillance studies to track immunity.

How Is the Sample Collected?

A small amount of blood is drawn from a vein in your arm by a healthcare professional. The blood is then separated into serum or plasma for testing.

What Are the Possible Results?

Results are typically reported as positive or negative. A positive result suggests the presence of antibodies, indicating past infection. A negative result means no detectable antibodies were found at the time of testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Anti-Nucleocapsid Antibody Test

Frequently asked questions

How soon after infection can antibodies be detected?
Antibodies to the nucleocapsid protein can begin appearing in the blood about 1–3 weeks after infection and may remain detectable for months or longer. However, antibody levels can vary widely among individuals.
Can this test be used to confirm vaccination status?
No, this test specifically looks for antibodies to the nucleocapsid protein, which are associated with a past SARS-CoV-2 infection. It does not directly measure immunity from vaccination. Vaccination status is typically confirmed through other tests or documentation.
What if my test result is positive but I never had symptoms?
A positive result could mean you had a mild or asymptomatic infection, which your body may have cleared without noticeable symptoms. Antibodies can also persist for a long time after recovery, so this does not necessarily indicate ongoing infection.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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