Fluorescent Antibody Virus IgG Immunoassay (Serum)
This test measures the presence of antibodies in your blood that your immune system produces in response to exposure to the flu virus. It helps determine if you’ve been infected or vaccinated.
["This test checks for immunity to flu viruses by detecting antibodies your body makes after exposure or vaccination."]
Key facts at a glance
- LOINC
- 9533-1
- Short code
- FLUAV IgM Titr Ser
- Synonyms
- FLUAV IgM Titr Ser
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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
Why This Test Is Done
Doctors may order this test if you have symptoms of the flu (like fever, cough, or body aches) and recent exposure to someone with the flu, or if you’re unsure whether you’ve been vaccinated. It can also be used to confirm a flu diagnosis or check immunity before travel or seasonal vaccination.
What to Expect Before the Test
No special preparation is needed. A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. If you’re on blood thinners, let your provider know before the test.
What the Test Results Mean
Positive results indicate the presence of flu-specific antibodies, suggesting past infection or vaccination. Negative results mean no detectable antibodies, which could mean you haven’t been exposed or vaccinated recently. Results don’t confirm active flu infection without clinical symptoms.
Common Causes of Positive Results
A positive result may occur after natural flu infection, vaccination (including flu shots or nasal sprays), or exposure to the virus. It can also appear in people who have had the flu in the past and developed immunity.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is useful for confirming flu exposure or vaccination status, especially in high-risk groups like elderly adults, pregnant women, or those with chronic health conditions. It helps guide decisions about antiviral treatments, vaccination, or further testing if symptoms persist. However, it’s not a direct test for active flu infection and should be interpreted alongside clinical symptoms and other diagnostic criteria.
Short name
IgG Antibody to Flu Virus (Serum)
Frequently asked questions
What does a positive result mean?
Can this test be used to diagnose active flu?
How long after exposure or vaccination might I get positive results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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