CDC H1N1 Flu | Influenza Diagnostic Testing During the 2009-2010 Flu Season

QUESTIONS & ANSWERS
Influenza Diagnostic Testing During the 2009-2010 Flu Season
September 29, 2009, 6:00 PM ET

For the Public
How will I know if I have the flu this season?
You may have the flu if you have one or more of these symptoms: fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue and sometimes, diarrhea and vomiting. Most people with 2009 H1N1 have had mild illness and have not needed medical care or antiviral drugs, and the same is true of seasonal flu. (More information is available on What To Do If You Get Sick this flu season.) Most people with flu symptoms do not need a test for 2009 H1N1 because the test results usually do not change how you are treated.

How can I know for certain if I have the flu this season?
To know for certain, a test specific for flu would need to be performed. But most people with flu symptoms do not need a test for 2009 H1N1 flu because the test results usually does not change how you are treated.

What kinds of flu tests are there?
A number of flu tests are available to detect influenza viruses. The most common are called “rapid influenza diagnostic tests” that can be used in outpatient settings. These tests can provide results in 30 minutes or less. Unfortunately, the ability of these tests to detect the flu can vary greatly. Therefore, you could still have the flu, even though your rapid test result is negative. In addition to rapid tests, there are several more accurate and sensitive flu tests available that must be performed in specialized laboratories, such as those found in hospitals or state public health laboratories. All of these tests are performed by a health care provider using a swab to swipe the inside of your nose or the back of your throat. These tests do not require a blood sample. For more information, see Seasonal Influenza Testing.

How well can these tests detect the flu?
Rapid tests vary in their ability to detect flu viruses. Depending on the test used, their ability to detect 2009 H1N1 flu can range from 10% to 70%. This means that some people with a 2009 H1N1 flu infection have had a negative rapid test result. (This situation is called a false negative test result.) Rapid tests appear to be better at detecting flu in children than adults. None of the rapid tests currently approved by the Food and Drug Administration (FDA) are able to distinguish 2009 H1N1 flu from other flu viruses.

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CDC H1N1 Flu | Influenza Diagnostic Testing During the 2009-2010 Flu Season