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

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

This test measures antibodies in your blood that your immune system produces in response to exposure to the SARS-CoV-2 virus, which causes COVID-19. It helps determine if you’ve had prior infection and may have developed immunity.

Quick summary

["This test checks for long-term immune response after COVID-19 infection."]

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

Key facts at a glance

LOINC
30493-1
Short code
Deprecated S pneum19 IgG sp2 Ser-mCnc
Synonyms
Deprecated S pneum19 IgG sp2 Ser-mCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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?

The test detects IgG antibodies specific to the spike protein of the SARS-CoV-2 virus. IgG antibodies are part of your immune system’s memory response and can persist for months or years after infection, indicating a past exposure to the virus.

Why Might You Need This Test?

Healthcare providers may order this test to assess whether you’ve developed immunity after recovering from COVID-19, evaluate vaccine response, or monitor long-term immune status in certain high-risk groups.

How Is the Test Performed?

A blood sample is drawn from a vein in your arm. The serum portion is then tested using an immunoassay method to detect IgG antibodies against the virus’s spike protein.

What Are Possible Results?

A positive result suggests you’ve likely had prior exposure to SARS-CoV-2 and may have developed immunity. A negative result means the test did not detect these antibodies, which could indicate no prior infection or insufficient time since exposure.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

SARS-CoV-2 IgG Antibody (Serum)

Frequently asked questions

How long do IgG antibodies last after COVID-19?
IgG antibodies can remain detectable for months to years after infection, but their exact duration varies by individual. Some people may still have detectable levels for over a year, while others may lose them sooner. Vaccination can also influence antibody levels.
Can this test confirm if I’ve had COVID-19 without symptoms?
While a positive IgG result strongly suggests prior infection, it does not definitively confirm asymptomatic cases. IgG alone cannot distinguish between natural infection and vaccine-induced immunity, so clinical history and other tests may be needed for full assessment.
What if my test is negative but I suspect I had COVID-19?
A negative IgG result means the test did not detect antibodies at this time. If you suspect past infection, consider testing with other markers (like IgM antibodies or PCR testing for recent exposure) or waiting longer—antibodies may take weeks to develop after 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