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Fluorescent Immunoassay for Antigen Detection in Influenza Virus (Type A or B)

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

This test detects the presence of influenza viruses (types A or B) in your respiratory secretions using a fluorescent antibody method. It helps quickly identify if you have an active infection caused by the flu.

Quick summary

["A rapid test to check for flu infection in your nose or throat samples."]

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

Key facts at a glance

LOINC
44560-1
Short code
FLUAV Ag Nose Ql IF
Synonyms
FLUAV Ag Nose Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 special fluorescent dye to bind to proteins found only in influenza viruses. When exposed to light, the dye glows, confirming the presence of the virus if it’s detected. This method is highly sensitive for detecting recent infections.

What to Expect Before the Test

You may provide a nasal or throat swab sample. The test is quick (often results in 15 minutes or less) and typically done at a clinic, urgent care, or sometimes at home if prescribed. No special preparation is needed.

When This Test Might Be Used

Doctors may recommend this test if you have flu-like symptoms (fever, cough, sore throat) and suspect influenza, especially during flu season. It’s also used in outbreaks or when rapid results are needed for treatment decisions.

Limitations and Considerations

This test detects recent infections but may not show past exposure. False negatives can occur if the virus is still low in your sample or if you’ve recently been treated with antiviral medications. It’s not a substitute for viral culture or PCR testing in some settings.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Influenza Antigen Test (FIA)

Frequently asked questions

Why might my doctor order this test?
Your doctor may order this test to confirm a flu diagnosis quickly, especially if symptoms are severe or if you’re at higher risk for complications (e.g., elderly, immunocompromised). Early identification allows for prompt treatment with antiviral medications if needed.
What does a positive result mean?
A positive result means the test detected influenza virus proteins in your sample, strongly suggesting you have an active flu infection. This can guide treatment decisions, such as starting antiviral drugs within 48 hours of symptom onset.
What if my symptoms improve before test results come back?
Symptom improvement doesn’t always mean the flu is gone. The test checks for the virus, not just symptoms. If you’re still contagious, you may need to isolate until symptoms resolve or the test confirms the virus is no longer present.
  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