Covid-19 Factsheet

Quest Diagnostics

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COVID-19

Quest Diagnostics

Patient and healthcare provider fact sheets for COVID-19 testing

Active infection testing

Antibody testing

Important information about COVID-19 antibody testing

The test is designed to detect antibodies to SARS-CoV-2, the virus that causes COVID-19. Antibodies are proteins that the body produces in response to infections. The antibodies can be produced even if a person has few or no symptoms during the infection.

It generally takes some time after infection for antibodies to be produced and become detectable in blood (sometimes up to 3 weeks). It is important to remember that we do not yet know whether having antibodies to SARS-CoV-2 will prevent against getting the infection again or if you are totally free of the virus. Antibodies are generally detectable in the blood for a period of time after a person has recovered from the infection and after the virus that caused the infection is no longer detectable by laboratory methods.

Sometimes the antibodies developed in response to an infection protect us from getting that same infection again. But, it is important to know that we do not yet know whether this is true for COVID-19. Even if you have recovered and have antibodies, there is a chance that you still have the virus and you can infect others, it is still critical to keep taking measures to avoid getting infected again and/or spreading infection.

The antibody test is not meant for detecting an active infection. The swab test (sometimes also known as a molecular, RNA or PCR test) should be used to test for active infection.

A negative antibody test result means that antibodies were not detected in your blood sample. This can have several possible meanings. It could mean that:

  • You have not been infected with SARS-CoV-2, or
  • You have been infected with SARS-CoV-2, but your antibodies have not reached a sufficient level for the test to be able to detect them, or
  • You have been infected with SARS-CoV-2, but there has not been enough time for antibodies to develop (it can take up to one to three weeks to develop antibodies after someone is infected, sometimes longer).

A positive antibody test result means that antibodies were detected in your blood sample. This can have a couple of possible meanings. It could mean that:

  • You have been infected with SARS-CoV-2 at some point in the past, or
  • Uncommonly, you may have developed antibodies from an earlier infection with a different virus related to SARS-CoV-2 and the laboratory test cannot distinguish between these other virus antibodies and those antibodies generated in response to SARS-CoV-2.

COVID-19 testing statements

  • The antibody tests and the molecular tests (together “All tests”) have not been FDA cleared or approved;
  • All tests have been authorized by FDA under EUAs for use by authorized laboratories;
  • The antibody tests have been authorized only for the detection of IgG antibodies against SARS-CoV-2, not for any other viruses or pathogens;
  • The molecular tests have been authorized only for the detection of nucleic acid from SARS-CoV-2, not for any other viruses, pathogens; and,
  • All tests are only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostics for detection and/or diagnosis of COVID-19 under Section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner.