Influenza virus identified

It is a respiratory infection caused by viruses. Respiratory infections may affect your nose, throat, and/or lungs. Most flu tests check a sample of fluid from your nose or throat to find out if you're infected with a flu virus.

If you have symptoms of a respiratory infection, a test for common seasonal flu may be used to help find out if the influenza A or B virus is causing your illness. Knowing whether you have the flu is especially important if you have a high risk of becoming seriously ill from the flu. The test results can help your provider decide if medicine could help treat your illness and which one might help you.