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.
A positive 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. See If You Are Sick: COVID-19.
Your close contacts will also be asked to stay home and away from others (quarantine). This advice does not change if they get tested and the result is negative. See Close Contacts and Tracing: 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 may need to retest to confirm a negative result. See Health Advisory: Antigen-based Tests for Detection of SARS-CoV-2 (PDF).
PCR and other molecular amplification tests detect the virus's genetic material.
- Most accurate tests for detecting the virus that causes COVID-19.
- 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. 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. Nasal swabs are fast and accurate, and they’re a good option for most people.
- 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 semi-permanent 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.
- Used whether or not you have symptoms.
- A positive PCR or other molecular amplification test result is considered a confirmed case of COVID-19, and public health workers will follow up with the person to give recommendations for how long to stay home.
Antigen tests, sometimes called rapid tests, look for specific proteins on the surface of the virus.
- Produce results more quickly than other tests.
- May not be as accurate, especially for people who do not have symptoms.
- Given with a nasal swab.
- A positive antigen test result is considered a probable case of COVID-19, but they are still considered cases and a public health worker will follow up with the person to give recommendations for how long to stay home.
Testing for past infection
Antibody tests, also called serology tests, tell if someone may have had SARS-CoV-2, the virus that causes COVID-19, in the past.
- Given by drawing blood via a finger stick.
- Cannot detect if you currently have COVID-19, only if you have had it in the past.
For questions about which test is right for you, talk to your health care provider.
What antibody tests cannot tell us
- An antibody test cannot tell someone if they currently have COVID-19. It can only tell someone if they may have had it in the past. A different lab test is used to tell if someone has it at the moment.
- 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.
Learn more at FDA: Coronavirus Disease 2019 Testing Basics.