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COVID-19 virus test

COVID 19 - Nasopharyngeal swab; SARS CoV-2 test

To test for the virus that causes COVID-19, a health care provider will take a mucus sample from your upper respiratory tract. This test is used to diagnose COVID-19.

The COVID-19 virus test is not used to test your immunity to COVID-19. To test if you have antibodies against the SARS CoV-2 virus, you need a COVID-19 antibody test.

How the Test is Performed

You will be asked to cough before the test begins and then tilt your head back slightly. A sterile, cotton-tipped swab is gently passed through a nostril and into the nasopharynx. This is the uppermost part of the throat, behind the nose. The swab is left in place for several seconds, rotated, and removed.

There are two types of virus tests available that can diagnose COVID-19:

  • Polymerase chain reaction (PCR) tests detect the genetic material of the virus that causes COVID-19. The samples  are usually sent to a laboratory for testing, and results are available in a few days. There are also rapid PCR diagnostic tests that are run on specialized equipment on-site, for which the results are available immediately.
  • Antigen tests detect specific proteins on the virus that causes COVID-19. Antigen tests are rapid diagnostic tests, which means the samples are tested on-site, and results are available in several minutes.
  • Rapid diagnostic tests of any kind are less accurate than the regular PCR test. If you get a negative result on a rapid test, but have symptoms of COVID-19, your provider may do a non-rapid PCR test.

If you have a cough that produces phlegm, the provider may also collect a sputum sample. Sometimes, secretions from your lower respiratory tract can also be used to test for the virus that causes COVID-19.

How to Prepare for the Test

No special preparation is needed.

How the Test will Feel

You may have slight or moderate discomfort and may gag.

Why the Test is Performed

The test identifies the SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus 2), which causes COVID-19.

Normal Results

The test is considered normal when it is negative. A negative test means that at the time you were tested, you probably didn't have the virus that causes COVID-19 in your respiratory tract. But you can test negative if you were tested too early after infection for COVID-19 to be detected. And you can have a positive test later if you are exposed to the virus after you were tested.

For this reason, if you have symptoms of COVID-19 or you are at risk for contracting COVID-19, your provider may recommend being retested at a later time.

What Abnormal Results Mean

A positive test means that you are infected with SARS-CoV-2. You may or may not have symptoms of COVID-19, the illness caused by the virus. Whether you have symptoms or not, you can still spread the illness to others. You should isolate yourself in your home and learn how to protect others from developing COVID-19. You should stay at home and away from others until you meet the guidelines for ending home isolation.

References

Centers for Disease Control and Prevention website. Coronavirus disease 2019 (COVID-19). Overview of testing for SARS-CoV-2. www.cdc.gov/coronavirus/2019-ncov/hcp/testing-overview.html. Updated July 17, 2020. Accessed July 22, 2020.

Centers for Disease Control and Prevention website. Interim guidelines for collecting, handling, and testing clinical specimens from persons for COVID-19. www.cdc.gov/coronavirus/2019-ncov/lab/guidelines-clinical-specimens.html. Updated July 8, 2020. Accessed July 22, 2020.

Kucirka LM, Lauer SA, Laeyendecker O, Boon D, Lessler J. Variation in false-negative rate of reverse transcriptase polymerase chain reaction-based SARS-CoV-2 tests by time since exposure [published online ahead of print, 2020 May 13]. Ann Intern Med. 2020;M20-1495. PMID: 32422057 pubmed.ncbi.nlm.nih.gov/32422057/.

  • COVID-19

    COVID-19 - illustration

    Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a respiratory illness that ranges from mild symptoms to pneumonia or even death. Symptoms occur within 2 to 14 days from exposure to the virus and may include fever, cough, shortness of breath, chills, muscle pain, headache, sore throat, and new loss of sense of taste or smell. COVID-19 may be more severe in people who are older or who have chronic health conditions, such as heart disease or diabetes.

    COVID-19

    illustration

  • Respiratory system

    Respiratory system - illustration

    Air is breathed in through the nasal passageways, travels through the trachea and bronchi to the lungs.

    Respiratory system

    illustration

  • Upper respiratory tract

    Upper respiratory tract - illustration

    The major passages and structures of the upper respiratory tract include the nose or nostrils, nasal cavity, mouth, throat (pharynx), and voice box (larynx). The respiratory system is lined with a mucous membrane that secretes mucus. The mucus traps smaller particles like pollen or smoke. Hairlike structures called cilia line the mucous membrane and move the particles trapped in the mucus out of the nose. Inhaled air is moistened, warmed, and cleansed by the tissue that lines the nasal cavity.

    Upper respiratory tract

    illustration

    • COVID-19

      COVID-19 - illustration

      Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a respiratory illness that ranges from mild symptoms to pneumonia or even death. Symptoms occur within 2 to 14 days from exposure to the virus and may include fever, cough, shortness of breath, chills, muscle pain, headache, sore throat, and new loss of sense of taste or smell. COVID-19 may be more severe in people who are older or who have chronic health conditions, such as heart disease or diabetes.

      COVID-19

      illustration

    • Respiratory system

      Respiratory system - illustration

      Air is breathed in through the nasal passageways, travels through the trachea and bronchi to the lungs.

      Respiratory system

      illustration

    • Upper respiratory tract

      Upper respiratory tract - illustration

      The major passages and structures of the upper respiratory tract include the nose or nostrils, nasal cavity, mouth, throat (pharynx), and voice box (larynx). The respiratory system is lined with a mucous membrane that secretes mucus. The mucus traps smaller particles like pollen or smoke. Hairlike structures called cilia line the mucous membrane and move the particles trapped in the mucus out of the nose. Inhaled air is moistened, warmed, and cleansed by the tissue that lines the nasal cavity.

      Upper respiratory tract

      illustration

    Self Care

     

    Tests for COVID-19 virus test

     
     

    Review Date: 4/11/2020

    Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 07/21/2020.

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