Types of COVID-19 Tests
Testing for current infection
Viral tests, sometimes called diagnostic tests, can detect if you have SARS-CoV-2, the virus that causes COVID-19. There are two types of diagnostic tests: molecular and antigen.
If you have questions about which test is right for you, talk to a health care provider.
A positive viral COVID-19 test (molecular or antigen test) means the person who took the test has COVID-19 and can spread it to others. If you get a positive test result, you should stay home and away from others. This advice does not change if you get a second test that is negative. Refer to If You Are Sick or Test Positive: COVID-19.
It generally is not recommended that people get tested again after getting a positive result. However, those who work in health care and long-term care should follow testing recommendations specific to those settings. Refer to Health Advisory: Antigen-based Tests for Detection of SARS-CoV-2 (PDF).
PCR, nucleic acid amplification tests (NAATs), and other molecular amplification tests detect the virus's genetic material.
- Molecular tests are the most accurate tests for detecting the virus that causes COVID-19.
- They can be used whether or not you have symptoms.
- They are given with a nasal swab, oral (throat) swab, or by taking a saliva sample.
- Nasal swab: A nasal swabs looks like a long Q-tip. It is inserted about two inches into your nose and swirled around for a few seconds. The swab is then removed and sent to a lab for testing. Nasal swabs are fast and accurate, and they’re a good option for most people. You may experience a tickling sensation while the swab is in your nose, and after it is removed, you might sneeze or have runny eyes for a moment or two. Health care providers are more likely to use nasal swabs that go farther into your nasal cavity, and you may feel more discomfort than when doing an at-home nasal swab.
- Saliva test: Saliva tests are self-administered; this means that after you are shown how to perform the test, you’ll do it by yourself. You will spit several times into a funnel attached to a tube, and then screw on a cap to complete the test. If you are at a community testing site, you will then hand your sample to a supervisor; if you are performing the test at home, you will put the sample into a prepaid UPS envelope and send it out. Most people need 10-12 minutes to make enough spit to fill the tube. Saliva tests are more comfortable than nasal swabs and just as accurate, but they may not be a good option for those with low saliva production, such as very young children or those who have suffered a stroke.
- A positive PCR, NAAT, or other molecular amplification test result is considered a confirmed case of COVID-19.
Antigen tests, sometimes called rapid tests, look for specific proteins on the surface of the virus.
- Antigen tests produce results more quickly than other tests.
- They are given with a nasal swab.
- A positive antigen test result means a person has COVID-19.
For more information on rapid tests that can be done at home, visit COVID-19 Self-Testing.
Testing for past infection
Antibody tests, also called serology tests, look for antibodies in your blood that fight the virus that causes COVID-19. Antibodies can be in your blood from either past infection or vaccination.
- Test blood collected by a finger stick or blood draw.
- A positive antibody test means a person may have antibodies from getting COVID-19 in the past or from COVID-19 vaccine.
What antibody tests cannot tell us
- An antibody test cannot tell you if you currently have COVID-19. If you receive a negative antibody test, it does not mean you do not currently have COVID-19. A molecular or antigen test must be used to determine if you have COVID-19 right now.
- Antibody tests cannot tell if someone can get COVID-19 again. We do not know yet how long antibodies for the virus that causes COVID-19 last or if they can keep people from getting it again.
- Most antibody tests cannot distinguish between antibodies acquired through infection versus vaccination.
Learn more at FDA: Coronavirus Disease 2019 Testing Basics.