This 3 minute video explains the basics of COVID-19 testing.
Order free self-test kits from COVIDtests.gov
Viral tests are swab or saliva tests.
Antibody tests (also known as serology tests) are blood tests.
VIRAL TESTS
(swab or saliva tests) |
ANTIBODY TEST
(blood tests) |
||
|
NUCLEIC ACID AMPLIFICATION TEST (NAAT) |
ANTIGEN TEST |
ANTIBODY TEST |
---|---|---|---|
How the test works |
Detects genetic material (RNA) within the COVID-19 virus |
Detects proteins (or antigens) on the surface of the COVID-19 virus |
Detects antibodies made by the immune system |
How the test is done |
Saliva, or swab from nose or throat |
Swab from nose or throat |
Blood from arm or finger stick |
How long it takes to get results |
Same day and up to 3 days. Some are rapid (around 20 minutes) |
Most are rapid, around 15 minutes or less |
Same day and up to 3 days |
Over the counter self-tests |
A few companies make them |
Many companies make them |
Not available |
*Includes PCR (e.g., Reverse-Transcriptase Polymerase Chain Reaction - RT-PCR) and Loop-Mediated Isothermal Amplification (LAMP)
The following information refers to COVID-19 viral tests.
Note: There may be other settings that have their own testing requirements.
Talk with your doctor to make sure you understand what your viral test result means and any next steps. If you did a home test and need advice about what to do next, you can also call the DPH COVID-19 information line at 1-833-540-0473.
SUMMARY: VIRAL TESTS - WHAT A RESULT MEANS | ||
|
NUCLEIC ACID AMPLIFICATION TEST (NAAT) |
ANTIGEN TEST |
---|---|---|
Positive Result* |
A positive result means the test found the COVID-19 virus. It is very likely you have COVID-19. You need to follow isolation instructions. |
A positive result means the test found the COVID-19 virus proteins. It is very likely you have COVID-19. You need to follow isolation instructions. |
Negative Result* |
A negative result means that the virus that causes COVID-19 was not found. |
A negative result means that COVID-19 virus proteins were not found.
|
*No test for COVID-19 is perfect. Any test may produce:
Your COVID-19 Test was POSITIVE (POS)
The test detected the COVID-19 virus. It is very likely you have COVID-19 and could spread it to others. For instructions on what to do next click on the situation that applies to you.
If you have symptoms of COVID-19
Important: If you are at high risk for getting very sick from COVID-19 you may be able to get medicine to help keep you out of the hospital. Contact a doctor right away even if your symptoms are mild. Don’t delay: the medicines work best when they are given as soon as possible after symptoms start. See ph.lacounty.gov/covidmedicines for more information.
If you don’t have symptoms of COVID-19
Important: If you are at high risk for getting very sick from COVID-19 you may be able to get medicine to help keep you out of the hospital. If you develop any symptoms, even if they are very mild, contact a doctor right away. Don’t delay: the medicines work best when they are given as soon as possible after symptoms start. See ph.lacounty.gov/covidmedicines for more information.
Your COVID-19 Test was NEGATIVE (NEG)
A negative COVID-19 result means the test did NOT detect the COVID-19 virus at the time you took the test. For instructions on what to do next click on the situation that applies to you.
If you have symptoms of COVID-19
It is possible that the test is wrong and that you are infected. This can happen if the test is taken too early or if the test misses your infection. If you continue to feel sick, keep staying away from others, and call your doctor about getting tested again.
Note: Even with a negative test, your doctor may still diagnose you with COVID-19 based on your history, symptoms, and your physical examination (if done).
*If your negative test is an antigen test and/or an over-the-counter self-test, it is recommended that you get another test a day later (antigen or NAAT) because these tests are more likely to miss early infections.
If you are not sure what kind test you got, look at your test result report, ask your doctor, or look on the webpage where you booked the appointment.
If you don’t have symptoms of COVID-19
If you are not a close contact, it is very unlikely you have COVID-19.
COVID-19 antibody tests (also known as serology tests) are blood tests that are used to look for antibodies to SARS-COV-2 (the virus that causes COVID-19). If we get COVID-19 or a COVID-19 vaccine our body’s immune system responds. It makes antibodies and prepares our immune cells to be ready to fight the virus in the future.
COVID-19 antibody tests do not look for the actual SARS-CoV-2 virus itself. They can be used to help figure out if someone was infected with COVID-19 in the past. It takes about one to three weeks after becoming infected for the body to make enough antibodies to be found by a test. Some people may take even longer, and some people who were infected with COVID-19 may never develop antibodies. NONE of the currently authorized tests are recommended to see if people have been successfully vaccinated against COVID-19.
When COVID-19 antibody tests may be useful
There are situations where antibody tests may be helpful. For example:
COVID-19 antibody tests cannot tell a person:
We do not know yet if having antibodies to the COVID-19 virus can protect someone from getting infected again or, if it does, how long that protection (immunity) might last. Even if you had a positive antibody test, you should continue to practice everyday prevention to protect yourself and others, including getting vaccinated. The vaccine is the best way to protect yourself from COVID-19.
Antibody tests are not 100% accurate, so false positives and negatives may occur. Talk to your doctor before being tested for antibodies. Your doctor can help you decide if you should be tested and, if you are tested, tell you what your results mean. To learn more about using antibody tests to look for past infection, visit the CDC webpage.