Frequently Asked Questions About COVID-19 Testing

Can someone test negative and later test positive on a viral test for COVID-19?

Yes, it is possible. You may test negative if the sample was collected early in your infection and test positive later during this illness. You could also be exposed to COVID-19 after the test and get infected then. Even if you test negative, you still should take steps to protect yourself and others. See Testing for Current Infection for more information.


Should I be tested for a current infection?
 

The following people should get tested for current COVID-19 infection:

• People who have symptoms of COVID-19.

• People who have had a known exposure to someone with suspected or confirmed COVID-19.

  • People who are fully vaccinated should get tested 3-5 days after exposure, and wear a mask in public indoor settings for 14 days or until they receive a negative test result.

  • People who are not fully vaccinated should quarantine and be tested immediately after being identified, and, if negative, tested again in 5–7 days after last exposure or immediately if symptoms develop during quarantine.

• People not fully vaccinated with COVID-19 vaccine who are prioritized for expanded community screening for COVID-19.

• People not fully vaccinated with COVID-19 vaccine who have been asked or referred to get testing by their school, workplace, healthcare provider, state, tribal, localexternal icon, or territorial health department.”

For more information on testing, see

• Testing for COVID-19

• Self-Testing

• Test for Current Infection

• Test for Past Infection
  
   

Types of COVID-19 Testing
 

You’ve probably heard a lot about coronavirus disease (COVID-19) testing. If you think you have COVID-19 and need a test, contact your health care provider or local health department immediately. You can also find a community testing site in your state, or buy an FDA-authorized at-home test. Some FDA-authorized at-home tests give you results within minutes. Others require you to mail the sample to a lab for analysis.

There are two different types of tests – diagnostic tests and antibody tests.

Diagnostic tests can show if you have an active

Covid-19 infection and need to take steps to quarantine or isolate yourself from others. Molecular and antigen tests are types of diagnostic tests than can detect if you have an active COVID-19 infection. Samples for diagnostic tests are typically collected with a nasal or throat swab, or saliva collected by spitting into a tube.

​

Antibody tests look for antibodies in your immune

system produced in response to SARS-CoV-2, the virus that causes COVID-19. Antibody tests should not be used to diagnose an active COVID-19 infection. Antibodies can take several days or weeks to develop after you have an infection and may stay in your blood for several weeks or more after recovery. Samples for antibody tests are typically blood from a finger stick, or blood drawn by your doctor or other medical personnel.

​