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Interferon-gamma release assay (IFN-γ) for SARS-CoV-2 (QuantiFERON-TB Gold Plus or similar TB/COVID-19 screening test)

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

This test measures your immune system’s response to a specific protein from the SARS-CoV-2 virus, helping detect past or potential exposure.

Quick summary

["Assesses immune activation linked to COVID-19 exposure, not active infection status."]

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

Key facts at a glance

LOINC
95971-8
Short code
SARS-CoV-2 IFN-g Bld Ql
Synonyms
SARS-CoV-2 IFN-g Bld Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What This Test Measures

The test evaluates your body’s production of interferon-gamma (IFN-γ), a protein released by immune cells when they detect the SARS-CoV-2 virus. This response helps determine if your immune system has been exposed to the virus, even if you don’t currently have symptoms or an active infection.

How the Test Works

Blood is drawn and mixed with two sets of viral proteins (one with SARS-CoV-2, one without). If your immune system recognizes the virus, it releases IFN-γ, which is measured to confirm exposure.

Why It’s Done

This test is often used in screening for COVID-19 exposure, especially in high-risk groups like healthcare workers, travelers, or individuals with weakened immune systems.

What It Doesn’t Show

This test does not diagnose an active COVID-19 infection. It only indicates whether your immune system has encountered the virus before, which may require additional testing for current infection.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IFN-γ release assay

Frequently asked questions

Can this test detect current COVID-19 infection?
No, this test measures immune response to past exposure, not active infection. For diagnosing current illness, a viral test (like PCR or rapid antigen) is needed.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on the lab processing time.
Is this test the same as a COVID-19 antibody test?
No, this is an interferon-gamma release assay (IGRA), which detects immune activation, while antibody tests measure specific antibodies produced later in 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