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How Is A Flu Test Performed

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What Is A Flu Swab Test

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A flu swab test is one of several options available for diagnosing influenza viruses in nasal, nasopharyngeal or throat specimens. Each of these tests requires that a healthcare provider rotate the inside of the patients nose, nasopharynx or the back of the individuals throat with a swab, then store and transport the swab according to the test type procedure for analysis.

These tests may vary in their effectiveness due to a number of reasons, including the number of flu variants circulating and the type of testing methodology and materials used. To ensure the most accurate possible results, it is important to select your flu test swab with care.

Cost Could Be An Issue

Users of the Labcorp Seasonal Respiratory Virus RT-PCR DTC Test self-collect nasal samples at home using a swab.

They then mail the sample to Labcorp for analysis. Results are delivered through an online portal, with referrals to a healthcare professional available as needed.

Test kits cost $169 and can be purchased in retail stores or online.

A Labcorp spokesperson told Healthline that the tests are available with no upfront cost to individuals who have health insurance and who meet clinical guidelines, such as having symptoms of a respiratory infection.

But Nichols said it remains unclear whether insurers will cover the full cost of the combination test. Van Tuyl added the price of the Labcorp test makes it unlikely that it will supplant the COVID-only tests already on the market.

There is a big cost difference between the single COVID-19 test and the combination test, she explained. It may not be worth the extra cost just to know you do or do not have the other viral illnesses.

Having the test available for purchase and use without a prescription makes it possible to use without taking time off work, school, or securing child care. For some people, that will be important and helpful, MacDonald told Healthline. Nonetheless, the price of $169 makes it prohibitive for many people to purchase.

Van Tuyl said the combination tests could have utility for testing people who are high risk, have high risk family members, or in pediatric patients.

How Do Doctors Diagnose Viral Gastroenteritis

Doctors often diagnose viral gastroenteritis based on your symptoms. If your symptoms are mild and last only a short time, you typically wont need tests.

In some cases, a medical history, a physical exam, and stool tests can help diagnose viral gastroenteritis. Your doctor may perform additional tests to check for other health problems.

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How Accurate Is A Rapid Flu Test

A rapid antigen flu test is the least accurate type of flu test. They have moderate sensitivity and high specificity.

Sensitivity refers to a test’s ability to determine that you have a disease or illness youre positive for the illness. The specificity of a test is its ability to determine that you dont have a disease or illness youre 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, its more likely that itll have a false-negative result and miss positive cases. High specificity means that false-positive results are rare.

What Other Tests Might My Doctor Order To Diagnose My Flu

Covid19 Coronavirus Test Is Performed In The Laboratory Stock Photo ...

Your healthcare provider may order a strep test to check for strep throat, an RSV test to check for respiratory syncytial virus, a virus that often infects young children and the elderly, or a sputum culture to look for bacterial and/or fungal causes of a respiratory infection. Your healthcare practitioner may also order blood tests such as a comprehensive metabolic panel or complete blood count to monitor the health and function of organs such as your lungs and kidneys.

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Quick Answers For Clinicians

In most healthy individuals, the flu is self-limited and uncomplicated. In high-risk individuals , the flu can result in serious complications, including hospitalization and increased mortality risk. The Infectious Diseases Society of America and the CDC recommend testing if the results will influence management decisions, such as whether to initiate antiviral therapy. If influenza has been documented in the area, testing is not necessary for otherwise healthy outpatients with signs and symptoms consistent with influenza. See the Indications for Testing section for specific testing recommendations.

Laboratory testing is the only way to distinguish between SARS-CoV-2 and the flu. Importantly, laboratory testing is also the only way to determine cases of viral coinfection. Infection with one respiratory virus does not exclude the possibility of infection with another because patients may be infected with more than one virus at the same time. When SARS-CoV-2, influenza, and respiratory syncytial virus are cocirculating , the National Institute of Health recommends cotesting to determine proper medical management.

Ideally, influenza testing should occur as soon as possible after illness onset, using respiratory specimens collected within 4 days of symptom onset.

What You Need To Know About Dual Covid

Yes, it is possible to have both viruses at the same time.

Both diseases can spread from close contact with someone who is infected. The viruses travel through droplets from talking, sneezing, or coughing. Physical contact can also cause infection. Covering your mouth and nose , washing hands regularly, and keeping your distance from others is the best way to prevent the spread.

Both conditions can spread before the symptoms appear. If you have been in contact with someone who might have the flu or COVID-19, it is important to know that flu symptoms take about 4 days to appear and COVID-19 symptoms take between 2 to 14 days to appear.

COVID-19 is considered more contagious by the CDC however both are highly contagious viruses. Covering your mouth and nose , washing hands regularly, and keeping your distance from others is the best way to prevent the spread. Additionally, the flu remains contagious up to 7 days after symptoms appear, while COVID-19 for up to 10 days.

Older adults, pregnant women, and people with underlying medical conditions are at risk of severe difficulties from both COVID-19 and the flu. Children and infants are at a higher risk for flu complications than COVID-19. However, children infected with COVID-19 are more vulnerable to rare complications like Multisystem Inflammatory Syndrome. Vaccines are available for both COVID-19 and the flu.

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What Are The Pros And Cons Of Rapid Influenza Diagnostic Tests

Advantages of the test

  • RIDTs produce quick results in less than 15 minutes and are simple to perform.
  • Some RIDTs are cleared for office/bedside use.

Disadvantages of the test

  • Sub-optimal test sensitivity and false-negative results are common, especially when influenza activity is high.
  • Sensitivity of RIDTs used to detect influenza B viral antigens is lower than those used to detect influenza A viral antigens.
  • Although specificity is high, false-positive results can also occur, especially during times when influenza activity is low.
  • Some RIDTs distinguish between influenza A and B viruses, while others do not.
  • RIDTs that provide results on the type of influenza virus do not provide information on influenza A virus subtype or specific virus strain. RIDTs cannot distinguish between seasonal influenza A virus infection and novel influenza A virus infection .

What Is Influenza A & B Testing

NEJM Procedure: Collection of Nasopharyngeal Specimens with the Swab Technique

Influenza A & B tests are rapid diagnostic tests that screen for influenza virus infection. In most cases, your Healthcare Clinic provider can diagnosis the flu based on symptoms, especially when these symptoms occur during the peak flu season. But sometimes he or she may want to perform an influenza rapid diagnostic test to be sure the influenza virus, not another health problem, is responsible for your symptoms.

To conduct the test, we will collect a specimen from the back of your nose or throat with a cotton-tipped swab.

The rapid diagnostic flu test usually provides results within 15 minutes.

This test is available at Healthcare Clinic locations for patients 18 months and older.

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Is There Anything Else I Should Know

Treated or untreated, most influenza infections will go away within one or two weeks, although fatigue and a cough may last a while longer. A few people, however, may develop serious secondary complications. These complications often arise just as influenza symptoms are fading.

Anyone is susceptible to complications from the flu, but the very young, the elderly, and people who are immunocompromised or who have pre-existing lung disease are most affected. Complications such as pneumonia, sepsis, and encephalitis can be very serious and may require immediate medical treatment.

How Accurate Is The Flu Test

Accuracy of the flu test depends on which kind of test is performed and the type of influenza thats going around. While RIDTs are the most common flu tests, they are not as accurate as molecular assays, and they seem to be better at detecting the flu in children than adults. In general, if you receive a positive rapid test during a flu outbreak, it likely means youre infected with the flu. Note that false negative and false positive test results can occur.

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How Do You Know If You Need A Flu Test

Your need for a flu test will come down to the symptoms to present to your doctor, and how they decide to diagnose those symptoms. The most common signs and symptoms of the flu, per the CDC, usually include:

  • Fever and chills
  • Cough
  • Fatigue or tiredness
  • Vomiting and diarrhea

You may realize that the symptoms listed above are also very common to those seen with COVID-19and if your doctor decides to test for that first, and it comes back negative, they will likely move on to a flu test, Robert L. Murphy, MD, a professor of infectious diseases at Northwestern Medicine Feinberg School of Medicine, tells Health.

Getting Tested For Influenza


Tests for influenza infection are often ordered by a doctor and conducted in a hospital, doctors office, or laboratory. Rapid flu tests may also be done in outpatient settings like health clinics or pharmacies.

Testing for influenza normally involves a swab of the area in the back of the nose, the inside of the nostril, and/or the throat. For most people, obtaining a sample is not painful and can be done in under a minute.

In addition to flu swabs, testing can be done with nasopharyngeal aspirates, which are samples removed through the nose with a suction device. Because they are more difficult and uncomfortable to obtain, nasopharyngeal aspirates are not commonly used for diagnostic testing.

The only type of flu testing that does not use a sample from the respiratory tract is serology testing, which is not used for flu diagnosis. Serology tests require a blood sample that is typically taken from a vein in the arm.

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How Is The Flu Diagnosed

Its common for healthcare providers to diagnose the flu based on symptoms and an exam, especially during flu season when the flu is going around your community. Oftentimes, a flu test isnt performed because if there is a high level of flu in the community and you have symptoms but test negative, guidelines recommend that you be treated anyway.

How Is A Flu Test Performed

All flu tests require a respiratory sample. This can include samples from:

  • Your nasal cavity with a swab.
  • Your nasal cavity through a wash or aspirate, meaning your healthcare provider injects a saline solution into your nose and removes the sample with gentle suction. This collection method is sometimes used on very young children.
  • The upper part of your throat with a swab through your nose.

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How Long Does A Flu Test Take

Getting a flu test isnt usually a time-consuming experience. Your healthcare professional may use one of several approaches to collect a specimen. These include:

  • Deep nasal swab. This testing method involves inserting a swab about one inch into the nostril. It doesnt require inserting as deeply as a nasopharyngeal swab .
  • Nasopharyngeal or nasal aspirate. A less commonly used method, this involves using a special suction catcher to suction mucus for sample collection. When the suction catheter is very far in the back of the throat, doctors call this nasopharyngeal aspirate.
  • Nasopharyngeal swab. For this test, youll be asked to tilt your head back, and a healthcare provider will swab both nostrils. The swab should be inserted to where theres an equal distance between the nostril and the outer ear opening.
  • Throat or nasal swab. This testing method involves using both a nasal swab as well as a throat swab that reaches back into the tonsil area of the throat.

Each of these testing methods usually takes no more than 1 minute to perform. Its waiting for your results that can prove longer.

Centers for Disease Control and Prevention , rapid flu tests are more accurate in detecting the flu in children compared with adults.

With these and other flu tests, its still possible to get a false negative. A doctor should take your symptoms into account as well as if youve been around anyone who was recently diagnosed with the flu.

Why Is The Flu Such A Big Deal

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The flu is an important general and public health concern because it can be deadly and because every few decades an especially lethal influenza strain emerges. The worst on record is the 1918 Spanish flu pandemic, which killed 20 to 50 million people worldwide, and more than 500,000 in the United States alone. In 1957 and 1968, hundreds of thousands died in the U.S. from Asian and Hong Kong flu variants.

In more recent years, there has been international concern about the H5N1 and H7N9 subtypes of influenza A, commonly called avian flu, and H1N1 flu. Some of these subtypes have caused outbreaks in humans, and there is concern that they may in the future cause more widespread and serious outbreaks. Read the article on Influenza to learn more about these.

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Influenza Virus Testing Methods

Table 1: Influenza Virus Testing Methods

Rapid Influenza Diagnostic Tests4 A and B NP5 swab, aspirate or wash, nasal swab, aspirate or wash, throat swab < 15 min.
Rapid Molecular Assay A and B
Immunofluorescence, Direct or Indirect Florescent Antibody Staining A and B NP4 swab or wash, bronchial wash, nasal or endotracheal aspirate 1-4 hours No
RT-PCR7 and other molecular assays A and B NP5 swab, throat swab, NP5 or bronchial wash, nasal or endotracheal aspirate, sputum Varies No
Rapid cell culture A and B NP5 swab, throat swab, NP5 or bronchial wash, nasal or endotracheal aspirate, sputum 1-3 days
Viral tissue cell culture A and B NP5 swab, throat swab, NP5 or bronchial wash, nasal or endotracheal aspirate, sputum 3-10 days No
  • Serologic testing is not recommended for routine patient diagnosis and cannot inform clinical management. A single acute serum specimen for seasonal influenza serology is uninterpretable and should not be collected. Serological testing for detection of antibodies to seasonal influenza viruses is useful for research studies and requires collection of appropriately timed acute and convalescent serum specimens and testing of paired sera at specialized research or public health laboratories.
  • Clinical Laboratory Improvement Amendments of 1988.
  • NP = nasopharyngeal
  • Rapid molecular assays can provide results in approximately 15-30 minutes.
  • VTM = Viral transport media
  • Weekly Respiratory Virus Detections Report

    The Respiratory Virus Detection Surveillance System monitors laboratory testing for flu and other respiratory viruses. Select laboratories across Canada report the number of tests performed and the number of tests positive each week.

    Reports are posted every Thursday and contain data on laboratory testing for influenza and respiratory viruses in Canada.

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    Viral Cell Culture Test

    Viral cell culture tests perform an extremely accurate and conclusive method for diagnosing influenza. Viral cell culture tests can determine the strain of virus and have become the most common test to help identify and track the spread of flu. However, results for these tests generally take 24 to 48 hoursor longeras they must be sent to a lab. Some cultures may take up to 10 days. As a result, these tests are a better option for population health support, such as documenting the specific strains of influenza active in a given population or region or tracking the effectiveness of antiviral agents. Viral cell cultures can also be used to confirm or refute a rapid flu test result.

    Think You Might Have The Flu Heres What To Do


    Feeling achy? Tired? Feverish? Wondering if you have the flu or even something else?

    If youre feeling a little off this season, then you may be considering a sick visit to your neighborhood MinuteClinic®. Seeking care for your flu-like symptoms is more important than ever, especially as we get closer to peak flu season, which typically hits the U.S. in February. Unfortunately, this years flu season is once again complicated by the presence of COVID-19. So, if youre feeling a little off, you may be wondering, Do I have the flu?, making it even more important to get checked, tested and treated as soon as you start to feel symptoms.

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    What Kinds Of Flu Tests Are There

    A number of tests are available to detect flu viruses in respiratory specimens. The most common are called rapid influenza diagnostic tests . RIDTs work by detecting the parts of the virus that stimulate an immune response. These tests can provide results within approximately 10-15 minutes but may not be as accurate as other flu tests. Therefore, you could still have flu, even though your rapid test result is negative. Other flu tests called rapid molecular assays detect genetic material of the flu virus. Rapid molecular assays produce results in 15-20 minutes and are more accurate than RIDTs.

    In addition to RIDTs and rapid molecular assays, there are several more accurate flu tests available that must be performed in specialized laboratories, such as those found in hospitals or public health laboratories. These tests include reverse transcription polymerase chain reaction , viral culture, and immunofluorescence assays. All of require that a health care provider swipe the inside of your nose or the back of your throat with a swab and then send the swab for testing. Results may take one to several hours.

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