Antibody Testing (COVID-19)

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Understanding Antibody testing is important to understanding how immunity to COVID-19 can and cannot be tested. Serology testing for antibodies test (antibody testing) is not recommended to determine if someone is immune or protected against infection. An antibody tests do check a person’s blood for the presence of antibodies, which show if you had a previous infection with COVID-19. Commercially available tests check for different types of antibodies. Only tests that check for the type of antibody that is known to neutralize, or kill, the virus tell if you are protected. The results of antibody tests are required to be reported to DHEC. Regulation and approval of these tests is done by the U.S. Food and Drug Administration (FDA).

DHEC follows CDC guidance and advises that antibody tests should not be used to determine if someone is immune, or protected, against infection with the SARS-CoV2 virus that causes COVID-19. For example, antibody tests cannot be used to make decisions about the need for quarantine. A positive or negative antibody test cannot be used to determine if someone responded to COVID-19 vaccination. 

Positive antibody tests can reliably confirm if someone has had a past infection. They are not reliable in determining if someone is currently infected and should not be used to make a diagnosis of current COVID-19 infection. Only a positive neutralizing antibody test result provides information about possible protection against a second infection. The adequate level of  protective antibodies that will prevent infection is still being studied. People should not rely on the results of antibody tests to make decisions about practicing prevention measures. DHEC recommends following recommended prevention measures, such as physical distancing and the use of a mask according to their vaccination status and disease activity in the community, 

Please see additional information about COVID-19 antibody testing below.

I am unvaccinated and have tested positive for COVID-19 antibodies. Do I have to quarantine after close contact with someone who is infected with COVID-19?

Re-infection with SARS-CV-2 within 3 months (90 days) of prior infection is rare. For this reason, unvaccinated people who have tested positive for SARS-Co-V-2 (antigen of PCR) within 3 months (90 days), and who have remained asymptomatic do not need to quarantine in low risk situations.

Individuals should still monitor themselves for symptoms of COVID-19 during the 14 days after exposure and if symptoms of COVID-19, develop they should isolate and seek testing.

Additional information about FDA approved antibody tests can be found here.

Will DHEC’s Public Health Laboratory offer antibody tests for COVID-19?

Our Public Health Laboratory does not plan to offer this testing at this time.

Does the presence of antibodies to COVID-19 mean the patient is infected?

Not necessarily. It may indicate a past infection that has been cleared or a current infection which began within the past week or two.

Does the presence of antibodies to COVID-19 mean the patient is no longer contagious?

No, patients can still be shedding infectious virus even though they have an antibody response. It also doesn’t mean that they are immune because we don’t know if their antibodies are enough to keep someone immune or for how long.

Does the presence of antibodies to COVID-19 mean the patient is immune to reinfection?

We don’t know that yet. The antibody tests do not indicate whether the antibodies are protective or not.

Are there any disadvantages or concerns with using the antibody tests, even the approved tests?

Patients who are told their antibody test is negative may decrease social distancing efforts, thinking they are not infectious. This could be dangerous because person with a negative antibody test is still vulnerable to becoming infected. The person could also already be infected and shedding virus to other people but not have developed antibodies yet.

Those who are told they have positive antibodies may feel that they are now “immune” from becoming infected with COVID-19 because they already had the virus although this has not been proven.  This could lead people to feel safe in crowds and not take adequate precautions.  Some people have tested positive for COVID-19 for a second time after already recovering from a previous infection.

Can we use antibody test to determine if an employee can go back to work?

Because the antibody test does not give information on the infectious status, or immunity from the disease, it is not useful for this purpose. We refer to the latest CDC guidance for when infected employees may return to work.


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