Flu (influenza) tests use a respiratory sample, such as a nasal or throat swab, to check for the presence of the flu virus. Your healthcare provider will perform these tests.
Yes. Flu tests require a respiratory sample, such as a nasal swab, to check for the presence of the flu virus.
The flu (influenza) is a respiratory infection caused by a virus (germ). It occurs most often during the winter and easily spreads from person to person from coughing, sneezing and/or touching contaminated surfaces. Most seasonal flu outbreaks are caused by the A and/or B flu viruses.
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There are several different flu tests, including:
RIDTs, also called flu antigen tests, are the most common type of flu test. They can identify the presence of influenza A and B, and they work by detecting the parts of the flu virus called antigens that trigger an immune response.
RIDTs usually involve inserting a swab into your nostril to get a sample.
RIDTs provide results within approximately 10 to 15 minutes, but they may not be as accurate as other flu tests. You could still have the flu even though your rapid test result is negative.
Rapid molecular assays are flu tests that detect the genetic material of the flu virus. They produce results in 15 to 30 minutes and are more accurate than RIDTs.
These tests use a nasopharyngeal (NP) swab. The sample is then sent to a laboratory for analysis. Healthcare providers also use this test for people who are in the hospital and have flu symptoms.
Other specialized laboratory flu tests are more accurate than RIDTs and rapid molecular assays. One of these tests is called reverse-transcription polymerase chain reaction (RT-PCR).
For these tests, a healthcare provider collects a sample and then sends the swab to a laboratory for testing. It may take one to several hours or days to get your results.
If you have flu-like symptoms or are concerned about possibly having the flu, talk to your healthcare provider. Most people don’t need a flu test and recover from the flu within a week or two, but a number of factors can contribute to your provider wanting you to get a flu test.
Symptoms of the flu include:
Your healthcare provider may order a flu test if you have risk factors for flu complications. Risk factors include:
You may also need to take a flu test so that public health officials or providers can figure out whether an outbreak of respiratory illness in a community, such as a school or nursing home, has been caused by the flu.
Public health officials and providers may also use specialized flu tests to identify the type of flu virus that’s causing infections.
All flu tests require a respiratory sample. This can include samples from:
During the sample collection, you may feel a gagging sensation or a tickle when you or your provider swabs your throat or nose. A nasal aspirate or wash may feel uncomfortable, but the discomfort is temporary.
The results for a flu test that’s tested in a laboratory will be either positive (viral RNA detected) or negative (viral RNA not detected). Rarely, the result may be inconclusive or have an indeterminate interpretation.
Laboratory tests are the most accurate kind of flu test. For these tests, your healthcare provider swabs your nasal cavity or the back of your throat through your nose and sends the sample to a lab for analysis.
A rapid antigen flu test (rapid influenza diagnostic test, or RIDT) is the least accurate type of flu test. They have moderate sensitivity (50% to 70%) and high specificity.
Sensitivity refers to a test's ability to determine that you have a disease or illness — you’re positive for the illness. The specificity of a test is its ability to determine that you don’t have a disease or illness — you’re negative for the illness.
A highly sensitive test means that there are few false-negative results, meaning fewer cases of illness are missed. Since a rapid flu test has moderate sensitivity, it’s more likely that it’ll have a false-negative result and miss positive cases. High specificity means that false-positive results are rare.
If you have any questions about your flu test, reach out to your provider. It may be helpful to ask the following questions:
Yes, there are at-home and laboratory tests that can check for influenza type A and B viruses and SARS-CoV-2, the virus that causes COVID-19, at the same time.
Some of the symptoms of the flu and COVID-19 are similar, so it can be hard to tell the difference between the two illnesses. If you have symptoms of the flu and/or COVID-19, contact your healthcare provider as soon as possible. They’ll likely recommend diagnostic testing, which can help determine if you are sick with the flu, COVID-19 or another respiratory infection.
A note from Cleveland Clinic
A flu test is a simple test your healthcare provider can perform on you or your child. While most people don’t need a flu test and recover from the flu within a week or two, certain factors can contribute to your provider wanting you to get a flu test. If you have any questions or concerns, feel free to reach out to your provider. They’re available to help.
Last reviewed by a Cleveland Clinic medical professional on 04/13/2022.
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