Coronavirus Disease 2019 (COVID-19)

If you have symptoms of coronavirus disease 2019, known as COVID-19, or you’ve been exposed to the COVID-19 virus, contact your healthcare team. Let them know if you’ve had close contact with anyone diagnosed with COVID-19.

In the United States, at-home COVID-19 tests are available. Free tests can be mailed to U.S. addresses, or you can purchase tests in stores, pharmacies or online. The U.S. Food and Drug Administration, also known as the FDA, approves or authorizes the tests. On the FDA website, you can find a list of the tests that are validated and their expiration dates. You also can check with your healthcare professional before buying a test if you have any concerns.

When taking a test at home, read the directions that come with the test carefully. Follow the instructions exactly to get as accurate a result as possible.

COVID-19 tests also are available from healthcare professionals, some pharmacies and clinics, or at community testing sites.

Here are some guidelines for when to take a COVID-19 test:

• If you have COVID-19 symptoms, test for the illness right away.
• If you were exposed to the COVID-19 virus but don’t have symptoms, wait at least five days after exposure then test.
• If you have symptoms and tested positive for COVID-19 within the last 30 days, you can test again. But if you were just exposed to the coronavirus and don’t have symptoms, you don’t need to test.

Also, testing before an event or contact with people at high risk of serious illness helps prevent the spread of the virus that causes COVID-19.

COVID-19 tests use a sample taken from your nose or throat, or a sample of saliva.

Two types of tests can help diagnose COVID-19.

• Molecular tests. These tests look for genetic material from the COVID-19 virus.

  Polymerase chain reaction tests, shortened to PCR tests, are molecular tests. You may also see this type of test called an NAAT test, short for nucleic acid amplification test.

  PCR tests are more accurate than the other type of COVID-19 test, called an antigen test. PCR tests may be done at home. But they are much more likely to be done by a healthcare professional and processed in a lab.

• Antigen tests. These tests look for viral proteins called antigens.

  Antigen tests also may be called rapid COVID-19 tests or at-home COVID-19 tests. These tests are useful if you need a quick result.

  Antigen tests are reliable and accurate, but they are less accurate than PCR tests. This is especially true if you don’t have symptoms. If you take an antigen test and are negative for COVID-19, take another antigen test after 48 hours to get the most accurate result.

Understanding test results

If you have a positive COVID-19 PCR or antigen test, you almost certainly have COVID-19. Another test isn’t needed.

If you get a negative PCR test, you most likely do not have COVID-19.

If you have a negative antigen test, the FDA recommends that you repeat an antigen test two days after the first test. With or without symptoms, repeating the test helps get the correct diagnosis.

If you test positive, call a healthcare professional immediately to find out what options are available.

Preventing the spread of the COVID-19 virus while sick

To prevent the spread of the COVID-19 virus to others, stay home and apart from anyone you live with for as long as you have worsening symptoms. If you have a weakened immune system, you will likely need to isolate for longer. How long depends on your symptoms and personal health history. Your healthcare professional can advise you on what’s best in your situation.

If you must be around others, a face mask helps lower the spread of this coronavirus. During this time, try not to share things like cups or towels, and use a separate bathroom and bedroom. It can help to get more airflow in your home as well.

Once you’re feeling better and haven’t had a fever for a full 24 hours, and you haven’t taken medicine for fever during that time, you can go back to being around others. If your fever returns or you start to feel worse, return to isolation until your symptoms improve and you are fever-free without medicine for 24 hours. But listen to the advice of your healthcare professional.

In the five days after isolation, to help prevent the spread of the COVID-19 virus you can wear a mask, wash your hands, keep your distance from others, test for COVID-19 infection and improve airflow. These actions are helpful even if you never had symptoms but tested positive for COVID-19.