Skip to content

COVID-19 Case Antigen Rapid Test (Serum/Plasma)

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

This test detects the presence of a specific protein (antigen) produced by the SARS-CoV-2 virus, which causes COVID-19, in your blood. It helps identify active infection rather than past exposure.

Quick summary

["Quickly checks for recent COVID-19 infection using a simple blood sample."]

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

Key facts at a glance

LOINC
95412-3
Short code
COVID-19 Case rprt
Synonyms
COVID-19 Case rprt
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
role
CPT
86592
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

How the Test Works

The test uses a rapid immunoassay method to detect viral antigens in your serum or plasma. When the virus is present, it triggers a chemical reaction that produces a visible result within minutes, indicating possible active infection.

What to Expect During the Test

You’ll provide a small blood sample, typically via a fingerstick or venipuncture. The sample is processed quickly, and results are available in about 15 minutes. This test is often done at a clinic or point-of-care setting.

When This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms of COVID-19 (e.g., fever, cough, fatigue), recent exposure to someone with COVID-19, or if you’re in a setting with high transmission risk. It’s not used for diagnosing past infection or vaccination status.

Limitations and Considerations

This test is designed for active infection detection and may not be as sensitive as PCR tests for all cases. False negatives can occur if the virus is not yet present in detectable amounts. Results should be interpreted by a healthcare professional.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

COVID-19 Antigen Screen

Frequently asked questions

Why might my doctor order this test?
Your doctor may use this test to confirm recent COVID-19 infection, especially if symptoms are mild or if other tests (like PCR) are unavailable. It helps guide treatment decisions, such as isolating at home or seeking further medical care.
What does a positive result mean?
A positive result strongly suggests you are currently infected with SARS-CoV-2 and should take steps to prevent spreading the virus to others, such as wearing a mask, staying home, and practicing good hygiene.
What does a negative result mean?
A negative result means the test did not detect the virus antigen at the time of testing, but this does not definitively rule out infection. You may still be infected if symptoms developed shortly before testing or if the virus is present in low amounts. Follow up with your doctor if symptoms persist.
  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