What you can expect

For a COVID-19 diagnostic test, a health care professional takes a sample of mucus from your nose or throat, or a sample of saliva. The sample needed for diagnostic testing may be collected at your doctor's office, a health care facility or a drive-up testing center.

• Nose or throat swab. A long nasal swab (nasopharyngeal swab) is recommended, though a shorter nasal swab or throat swab is acceptable. Your doctor or other health care professional inserts a thin, flexible stick with cotton at the tip into your nose or brushes the swab along the back of your throat to collect a sample of mucus. This may be somewhat uncomfortable.

  For the nasal sample, swabbing may occur in both nostrils to collect enough mucus for the test. The swab remains in place briefly before being gently rotated as it's pulled out. The sample gets sealed in a tube and sent to a lab for analysis.

• Saliva sample. Some locations offer saliva tests. While a saliva sample may be a bit less sensitive than a mucus sample that's taken using a long nasal swab, a saliva test is easier to do and often less uncomfortable. You spit into a tube several times to provide a sample of your saliva to test. The tube is sealed before being sent to a lab for analysis.

If you have a productive cough, your doctor may collect a sputum sample, which contains secretions from the lungs, a part of the lower respiratory system. The virus is more concentrated in the nose and throat early in the course of the infection. But after more than five days of symptoms, the virus tends to be more concentrated in the lower respiratory system.

In addition to the COVID-19 diagnostic test, your doctor may also test for other respiratory conditions, such as influenza, that have similar symptoms and could explain your illness.

The FDA granted emergency use authorization for certain at-home COVID-19 test kits, including one that tests for both COVID-19 and the flu. Most of these tests require a doctor's prescription. You collect your own sample of nasal fluid or saliva at home and then send it to a lab to be rapidly analyzed. One COVID-19 test provides fast results at home without sending the sample to a lab. And the FDA recently authorized an antigen test to buy over the counter with no prescription needed, though antigen tests are not considered as reliable as PCR tests.

The accuracy of each of these tests varies, so a negative test does not completely rule out having the COVID-19 virus. Only get an at-home test that's authorized by the FDA or approved by your doctor or local health department.