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IgG Antibody to SARS-CoV-2 (Spike Protein) (Serum)

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

This test measures the level of IgG antibodies in your blood that your immune system produces in response to the spike protein of SARS-CoV-2, the virus responsible for COVID-19. These antibodies indicate that your body has likely been exposed to the virus at some point.

Quick summary

["IgG antibodies help your immune system remember the virus for future protection."]

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

Key facts at a glance

LOINC
27429-0
Short code
Deprecated S pneum19 IgG sp2 Ser IA-mCnc
Synonyms
Deprecated S pneum19 IgG sp2 Ser IA-mCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
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?

IgG antibodies are a type of immune protein your body creates after encountering the SARS-CoV-2 virus. They play a key role in long-term immunity by helping your immune system recognize and fight off the virus if you become infected again. This test specifically looks for antibodies against the spike protein, a key part of the virus’s surface that helps it enter human cells.

Why Might You Need This Test?

Doctors may order this test to assess your immune response after recovering from COVID-19, to evaluate past exposure, or to monitor immunity in certain clinical situations. It can also help determine if you have developed immunity that may protect you from future infections.

When Is This Test Used?

This test is often used in research, clinical trials, or specialized care settings to understand your immune status following COVID-19 infection. It’s not typically used for routine screening or diagnosing active COVID-19, as other tests (like PCR or antigen tests) are preferred for that purpose.

What Does a Positive Result Mean?

A positive result means your blood contains IgG antibodies against the SARS-CoV-2 spike protein, suggesting your immune system has recognized and responded to the virus. This does not confirm a current infection but indicates past exposure and potential immunity.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Anti-Spike Antibody

Frequently asked questions

What Does a Negative Result Mean?
A negative result means your blood does not currently contain detectable IgG antibodies against the spike protein. This could mean you have not been exposed to the virus recently, or if you have been infected, your immune system may not have produced detectable antibodies at this time. It does not rule out past infection without antibody presence.
Can a Negative Result Still Indicate Past Infection?
Yes, a negative IgG antibody test does not always mean you were never infected. Some people may not develop detectable antibodies after infection, especially if their immune response was weak or if the infection was mild. Other tests, such as PCR or antigen tests, may be needed to confirm past infection if clinical suspicion remains.
How Long Do These Antibodies Last?
IgG antibodies against SARS-CoV-2 can persist for months or years after infection, but their levels may gradually decrease over time. Some people may still have detectable antibodies for a long period, while others may lose them. This can vary widely among individuals, and antibody levels do not always correlate perfectly with long-term immunity.
  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