COVID-19 test

Definition

To test for the virus that causes COVID-19, a health care provider will take samples of the secretions from your upper respiratory tract.

A nasopharyngeal swab examines a sample of secretions from the uppermost part of the throat, behind the nose, to detect the virus that causes COVID-19.

Alternative Names

COVID 19 - Nasopharyngeal swab; SARS CoV-2 test

How the Test is Performed

To collect a nasopharyngeal swab, 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 part of the pharynx that covers the roof of the mouth. The swab is left in place for several seconds, rotated, and removed.

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.

The samples will be sent to a laboratory for testing. The laboratory will perform an analysis called real-time RT-polymerase chain reaction (rRT-PCR). This analysis detects the genetic material of 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 still have a positive test later if you are exposed to the virus after you were tested.

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.

Images

COVID-19
Respiratory system
Upper respiratory tract

References

Centers for Disease Control and Prevention website. Evaluating and testing persons for coronavirus disease 2019 (COVID-19). www.cdc.gov/coronavirus/2019-ncov/hcp/clinical-criteria.html. Updated March 14, 2020. Accessed April 11, 2020.

Centers for Disease Control and Prevention website. Interim guidelines for collecting, handling, and testing clinical specimens from persons for coronavirus disease 2019 (COVID-19). www.cdc.gov/coronavirus/2019-ncov/lab/guidelines-clinical-specimens.html. Updated April 8, 2020. Accessed April 11, 2020.

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.