Fluorescent Antibody Titration for Viral Hemagglutination Inhibiting Antibodies (VHI)
This test measures the level of antibodies in your blood that can block a specific virus’s ability to attach to cells. It helps assess immunity or exposure to certain viruses, such as influenza.
["This test helps determine if your immune system has developed protection against a virus like flu."]
Key facts at a glance
- LOINC
- 47446-0
- Short code
- FLUAV H11 Ab Titr Ser
- Synonyms
- FLUAV H11 Ab 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
- 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
Your healthcare provider may order this test if you have symptoms of a viral infection, have been exposed to a virus, or if you’re being evaluated for immunity before receiving a vaccine. It can also be used to monitor treatment responses or diagnose chronic infections.
How the Test Works
A small blood sample is taken and tested in a lab. The sample is mixed with the virus and antibodies are detected using a fluorescent marker. The titer (or highest dilution) at which fluorescence is still observed indicates your antibody level.
Sample Collection
A vein in your arm is cleaned and a needle is inserted to draw blood. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood is then sent to a lab for testing.
What to Expect Before the Test
No special preparation is needed, but inform your provider about any medications or conditions that could affect results, such as recent infections or immune-suppressing treatments.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test plays a key role in diagnosing viral infections, evaluating immunity, and guiding vaccination protocols. High antibody titers may indicate past infection or immunity, while low or absent titers suggest a lack of protection.
Short name
Viral Hemagglutination Inhibition Antibody Titer
Frequently asked questions
What Does a Positive or Negative Result Mean?
How Long Does It Take to Get Results?
Can I Have This Test at Home?
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