Influenza A&B Testing

When do you need an influenza a&b test?

Many kinds of respiratory illnesses exhibit the same signs and symptoms as that of influenza infection. Even during flu season, it would be hard for doctors to determine whether you contracted the influenza virus based on symptoms alone. 

So to come up with a proper diagnosis, your physician may require you to undergo an influenza diagnostic test if:

• You are experiencing the common signs and symptoms of the flu.
• You don’t have any symptoms but are in close contact with a symptomatic person.
• You came from the hospital and started exhibiting respiratory illness symptoms. 

Getting tested right away will help prevent or limit the spread of the infection, especially if you’re living with high-risk individuals. Additionally, an influenza diagnostic test will aid in ruling out other contagious illnesses (e.g., COVID-19) so your doctor can provide the appropriate treatment options.

What are the different types of influenza diagnostic tests?

An influenza test is a procedure performed to detect the presence of the influenza virus. There are a lot of influenza a&b tests available, and they may vary in their methods, specimen of choice, test time, and accuracy. Some examples include:

• Rapid influenza diagnostic test or RIDT
• Rapid molecular assay
• Influenza A and B antibody test
• Immunofluorescence (direct or indirect)
• RT-PCR

Out of these tests, the most common ones performed in most clinics and urgent care facilities are the RIDT, rapid molecular assay, and antibody testing.

Rapid influenza diagnostic test or RIDT

RIDT, or flu rapid test, is the fastest and most common type of flu test that can tell whether or not you contracted the flu virus. This point-of-care testing can detect influenza A and B through the viral antigen (protein components of the virus) present in the patient’s respiratory sample.

A healthcare professional can perform this test by inserting a swab into the nostrils or throat to get a respiratory sample. The collected sample will then be processed using the RIDT kit, which can provide results within 15 minutes. 

Most RIDT kits resemble that pregnancy test kits in structure and result interpretation:

• Positive (two lines) - if the kit shows two vertical lines, it means that the sample is positive for the presence of the influenza virus. Your doctor will consider this result, your medical history, and your current symptoms in making a proper diagnosis.

• Negative (one line) - a single vertical line in the RIDT kit means that it did not detect the presence of the influenza viral antigen in the sample. However, this does not completely rule out influenza as the cause of your illness. Your doctor will still need to order a confirmatory test (e.g., RT-PCR or viral cell culture) to rule out the possibility of false negatives.

Furthermore, most RIDTs have a moderate sensitivity or accuracy of 50%-70% and 75%-80% (depending on the kit used). This means that they may only be used for diagnostic purposes.

Rapid molecular assay

A rapid molecular assay is another type of influenza a&b test that determines the presence of the influenza virus by detecting its genetic material or RNA. This type of antigen testing can differentiate between influenza A and B, thus making it more accurate and sensitive than RIDTs.

Rapid molecular assays also use nasopharyngeal swabs as their sample and provide results within 15 to 30 minutes. However, samples are required to be analyzed by a medical technologist using a machine or analyzer. This means that this flu rapid test is not readily available in most primary and urgent care facilities.

Influenza antibody testing

An influenza A and B antibody test detects the presence of antibodies in the body using a serum blood sample. This procedure will determine if you have antibodies against the influenza virus, which your body naturally produces when you get infected.

However, this type of influenza test is not routinely used since antibodies take time to develop. Additionally, antibody testing requires complex procedures, thus not providing timely results.

How is an influenza a&b test performed?

Most diagnostic and confirmatory tests for influenza require a nasopharyngeal swab sample. A healthcare provider will:

• Insert a swab stick into the nostril and collect respiratory secretions and cells. 
• The same swab may then be used to collect secretions from the other nostril.
• For RIDTs, the swab sample will be mixed with a specific reagent (it comes with the kit). This mixture will then be poured onto the sample well of the RIDT kit. Results can be seen within a minute, but your healthcare provider must wait at least 5 to 10 minutes before interpreting it.
• For rapid molecular assays, the swab sample will be placed in a transport tube and sent to the laboratory for analysis.

Some types of influenza tests may also use throat swabs, nasal wash, and serum blood as specimen samples.

Where can you get a test for the flu in Palm Beach County and the surroundings?

Flu season or not, it’s vital to get tested against the flu if you are experiencing any of its symptoms. At Urgent Care of the Palm Beaches, we provide a convenient and hassle-free way to get yourself tested at one of our locations:

• Test for the flu in West Palm Beach at our Urgent Care in West Palm Beach

• Test for the flu in North Palm Beach at our Urgent Care in Palm Beach Gardens

• Test for the flu in Palm Springs at our Urgent Care in Palm Springs

If you want to get a flu shot in Palm Beach County or require other medical services, then you can get an appointment or visit one of our facilities. Contact us to learn more!

The material contained on this site is for informational purposes only and DOES NOT CONSTITUTE THE PROVIDING OF MEDICAL ADVICE, and is not intended to be a substitute for independent professional medical judgment, advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare providers with any questions or concerns you may have regarding your health.