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Interferon-gamma Release Assay (IGRA) for SARS-CoV-2 T-Cell Response (Blood)

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

This test measures your immune system’s response to SARS-CoV-2 by detecting interferon-gamma produced by T-cells when exposed to viral antigens. It helps determine if you’ve had prior exposure to the virus, even if you don’t show symptoms.

Quick summary

["Assesses past COVID-19 exposure through immune memory, not current infection status."]

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

Key facts at a glance

LOINC
95973-4
Short code
SARS-CoV-2 IFN-g T cells Bld-aCnc
Synonyms
SARS-CoV-2 IFN-g T cells Bld-aCnc
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

How the Test Works

Your blood is collected and mixed with two sets of viral antigens: one from SARS-CoV-2 and one control antigen. If your T-cells recognize the COVID-19 virus, they release interferon-gamma, which is detected to confirm exposure. The result is qualitative (positive/negative) rather than a numeric measurement.

What to Expect Before the Test

No special preparation is needed. You may eat or drink normally before your blood draw. Wear comfortable clothing and plan to stay near the testing site for about 15 minutes afterward, as you’ll need to rest briefly after the draw.

What to Expect During the Test

A healthcare provider will insert a small needle into your arm to collect a blood sample. You may feel a brief pinch, but it’s usually over quickly. The test itself takes only a few minutes, and you’ll receive your results within 48 hours.

Possible Results and Next Steps

A positive result indicates your immune system has detected past exposure to SARS-CoV-2, meaning you’ve likely had COVID-19. A negative result suggests no detectable immune response to the virus at the time of testing. Follow-up testing or guidance from your healthcare provider may be recommended based on your clinical situation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

T-Spot COVID-19 Test

Frequently asked questions

Why might my doctor order this test?
Your doctor may recommend this test if you’ve had symptoms of COVID-19 but tested negative with a rapid antigen test, or if you’re at higher risk for infection (e.g., immunocompromised individuals, frequent travelers, or those in close contact with someone infected). It can also help assess immune response in vaccine studies or research settings.
Can this test replace a COVID-19 PCR test?
No, this test does not detect active infection. It measures your immune system’s memory of past exposure, not whether you currently have the virus. For diagnosing active COVID-19, a PCR test or rapid antigen test is still needed.
How long do I need to wait for results?
Results are typically available within 48 hours after the blood draw. Your healthcare provider will contact you directly with the outcome, so check your contact information with them to ensure you receive the results.
  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