Patient education: COVID-19 tests (The Basics)

What is COVID-19? — "COVID-19" stands for "coronavirus disease 2019." It is caused by a virus called SARS-CoV-2. The virus first appeared in late 2019 and quickly spread around the world.

What are the different types of COVID-19 tests? — There are 2 main types of tests used to diagnose COVID-19:

●Molecular tests – These look for the genetic material from the virus. They are also called "nucleic acid tests" or "PCR tests." You can get a molecular test at a doctor's office, clinic, or pharmacy. Depending on the lab, it can take up to several days to get test results back. Some molecular tests can be done at home.

●Antigen tests – These look for proteins from the virus. They can give results faster than most molecular tests. You can buy antigen tests to use at home. You can also get an antigen test at a doctor's office, clinic, or pharmacy.

There is also a type of blood test that can show if a person has had COVID-19 in the past:

●Antibody tests – These are generally not used on their own to diagnose COVID-19 or make decisions about care. But public health experts can use them to learn how many people in a certain area were infected without knowing it.

When should I get a COVID-19 test? — You should get tested if:

●You have a fever, cough, cold symptoms, or other symptoms of COVID-19.

●You were exposed to someone with COVID-19.

You can use the flowchart to figure out when to test and what to do based on the results (algorithm 1).

Which type of test should I get? — It depends:

●Molecular tests are the best way to know if you have COVID-19. That's because they can detect even very low levels of virus in the body. But they can be harder to get and can take longer to give results.

●Antigen tests are quick and easy to do at home. But they are not as accurate as molecular tests. They are more likely to give "false-negative" results. This is when the test comes back negative even though the person actually is infected.

In general, it is usually best to get whatever test is available to you the soonest. If you are not sure what to do, ask your doctor or nurse.

How do I do a COVID-19 test at home? — Most home tests are antigen tests. These involve using a swab to take a sample from inside of your nose. Different brands of tests have slightly different instructions for how to do this. Follow the instructions exactly to get accurate results. Do not mix parts from different tests.

In general, follow these steps:

●Wash your hands. If you are helping someone else do the test, such as a child, wear a face mask.

●Collect the sample from your nose – Use the swab that comes in the kit. Make sure that you know how far into your nostril to put it, and how long to swab for. You might need to get a sample from both nostrils.

●Test the sample – For some tests, you mix it with the liquid that comes in the kit, then put it on a test strip or card. For others, you put the swab with the sample directly into the test card.

●Wash your hands again.

●Wait for results – Results usually take about 15 minutes, but check the instructions. Set a timer to make sure that you know how much time has passed.

●Check your results when the time is up – The instructions will tell you exactly what to look for, and how to know if your test is positive or negative.

Some home tests are molecular tests. Follow the instructions carefully for these.

What will happen if I get a COVID-19 test from a doctor, nurse, or pharmacy? — Someone will collect your sample, or tell you exactly how to collect it yourself. If you are getting a molecular test, this might involve taking a sample from your nose, throat, or mouth. Some tests use saliva.

Then, they will send your sample to a lab for testing. You will get your results when they are ready. This might happen by phone, email, or through an online "patient portal."

What happens if I get a positive COVID-19 test? — If you test positive on either an antigen or molecular test:

●You should "self-isolate" for at least 5 days, even if you feel well. Self-isolation means staying apart from other people, even the people that you live with. The 5 days should start the day after you first noticed symptoms or got a positive test result. If you have a weak immune system or if you still have a fever, you might need to self-isolate for longer than 5 days.

●After self-isolating for 5 days, wear a mask around all other people for at least 5 more days. Some people use antigen tests to decide how long to keep wearing the mask. If you do this, you can stop wearing a mask once you test negative on 2 antigen tests done at least 2 days apart.

●If your symptoms are severe, or if you are at risk for severe illness, call your doctor or nurse. They can tell you if you need to be seen. Depending on your situation, they might suggest treatment.

What if my test is negative? — COVID-19 tests, especially antigen tests, can give false-negative results. If you have symptoms or know that you were exposed to the virus, experts recommend "repeat testing." This means getting tested at least 1 more time a few days later if an antigen test is negative. If repeat tests are also negative, it is likely that you do not have COVID-19.

If you had a negative molecular test, this usually means that you do not have COVID-19. But in some situations, your doctor or nurse might suggest getting a repeat test to make sure.

More on this topic

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