In most cases, a doctor can diagnosis the flu is based on flu symptoms, especially when these symptoms occur during the peak flu season. But sometimes your doctor may want to perform an influenza rapid diagnostic test to be sure the influenza virus is responsible for your symptoms and not another health problem.

Why is a flu test helpful?

Seasonal influenza epidemics are responsible for between 3 million and 5 million cases of severe illness and between 250,000 and 500,000 deaths worldwide each year. On average, approximately 36,000 deaths due to seasonal influenza occur in the United States annually. Influenza viruses can also cause pandemics, such as the one that occurred in 1918 and killed at least 20 million people.

When your doctor distinguishes the flu virus from other viral infections, the doctor can prescribe antiviral drugs early in the illness when they are most effective. If the flu is diagnosed early (within 48 hours of showing flu symptoms), the antiviral drugs may alleviate the severity of the flu symptoms. After 48 hours, these drugs may not have any benefit in reducing flu symptoms. In addition, a flu test may help reduce the incidence of antibiotics being inappropriately used for the flu virus.

How does a flu test work?

First, your doctor will take a sample from the back of your throat or nose. To collect this sample, the doctor will use a cotton-tipped wooden stick and will simply rub the cotton tip at the back of your throat or inside your nose. The doctor will then seal the sample in a packet and send it to the lab for testing.

How long does it take to get flu test results?

The rapid diagnostic flu tests usually provide results within 30 minutes.

What does the flu test detect?

Some rapid flu tests detect only influenza A virus. Others can detect both influenza A and influenza B viruses. Still, some cases of the flu may be missed by the rapid tests.

WebMD Medical Reference

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