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Serum SARS-CoV-2 IgG antibody (qualitative) by immunoassay

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

This test checks for the presence of antibodies to the virus that causes COVID-19 in your blood. Antibodies are part of your immune system’s response to infection.

Quick summary

["IgG antibodies indicate past infection with SARS-CoV-2, helping determine immunity status."]

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

Key facts at a glance

LOINC
41991-1
Short code
SARS-CoV IgM Ser Ql IA
Synonyms
SARS-CoV IgM 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
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 protein your immune system produces in response to exposure to the SARS-CoV-2 virus. If you’ve been infected with COVID-19, your body may create these antibodies months after the initial illness. This test detects whether your serum contains these antibodies, which can help confirm past infection.

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 exposure risk in high-risk settings, or support decisions about vaccination status. It’s not a test for active infection but rather a marker of immune response.

How Is This Test Performed?

A blood sample is drawn from a vein, typically in your arm. The sample is then tested using an immunoassay method to detect IgG antibodies against the virus. Results are reported as either positive or negative, indicating the presence or absence of these antibodies.

What Do the Results Mean?

A positive result suggests you may have developed immunity to COVID-19 due to prior infection. A negative result means the test did not detect IgG antibodies at this time, which could mean you haven’t been infected recently or your immune response hasn’t produced detectable antibodies yet.

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?
IgG antibodies typically remain in your system for months or years after infection, but their levels can decline over time. While they suggest past exposure, they do not guarantee lifelong immunity. Healthcare providers may recommend follow-up testing if needed.
Can This Test Be Used to Confirm Vaccination Status?
No, this test specifically measures antibodies from a prior infection. For vaccination-related immunity, you may need additional tests or documentation of vaccination history.
Does a Negative Result Mean You’re Not Infected Now?
A negative IgG result means the test did not detect antibodies at this time, but it does not rule out recent infection. If you develop symptoms or test positive for COVID-19, you should seek medical attention immediately.
  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