The COVID-19 antibody test, or serology test, is a blood test used to find out if you have ever been infected with SARS-CoV-2, which causes coronavirus disease (COVID-19).
However, an antibody test alone cannot determine if you have ever had the COVID-19 virus.
Antibodies are proteins produced by the immune system in response to an infection.
Your immune system – a complex system of cells, tissues and organs – recognizes foreign substances in your body and helps fight infections and diseases.
After being infected with the COVID-19 virus, it can take 2-3 weeks for the immune system to develop enough antibodies to be detected by tests, so be careful not to test too soon.
Antibodies can be detected in your blood for months or more while you are recovering from COVID-19.
Although these antibodies may provide some immunity to the COVID-19 virus, the current evidence is not sufficient to conclude how long the other antibodies will last or the extent of the virus infection. to help protect the body if re-infected.
Antibody tests can detect certain types of antibodies associated with the COVID-19 virus:
Binding antibodies. This test is very commonly used to detect whether you have formed antibodies in response to a COVID-19 infection. But it does not indicate the extent or effectiveness of the immune response.
Neutralizing Antibodies. Less widely, is a new and more sensitive test method for detecting a subgroup of antibodies that can inactivate the virus.
We perform this test in case you are positive for the bound antibody.
It’s the next step to finding out how effective the antibody is in the middle of blocking the virus to help protect you against a re-infection with COVID-19.
Why it’s done?
Testing for COVID-19 may be done if:
+ Have you ever had symptoms of COVID-19 but never been tested?
You are about to have a medical procedure in a hospital or clinic, especially if you have tested positive for COVID-19.
+ You have been infected with the COVID-19 virus and want to donate an antibody-containing component of blood, plasma, which can help treat patients who are severely infected with COVID-19.
If a child is sick and the doctor suspects childhood multisystem inflammatory syndrome (MIS-C), antibody testing may help with diagnosing MIS-C. Many children with MIS-C also have antibodies to COVID-19, indicating that they have had the coronavirus.
The results of a COVID-19 antibody test may not always be completely accurate, especially if we perform the test too soon after infection, or the quality of the test is in question.
A number of different manufacturers rush to put antibody tests on the market with less scrutiny. Currently, the U.S. Food and Drug Administration will publish data on the effectiveness of online antibody tests.
COVID-19 antibody testing can lead to false-positive and negative results:
+ False positive results. The result is positive, but you don’t actually have antibodies and you’ve never had the virus. A false positive can give you a false sense of security that you are protected against a future COVID-19 infection – and even with a true positive, immunity is questionable.
+ False negative results. You have antibodies to the COVID-19 virus, but the test doesn’t detect it. Your doctor could have taken the bood sample too soon after the infection has started and your body hasn’t had enough time to form antibodies.
How to prepare for the test
Your doctor or testing center will tell you where and how to get the test. Please pay attention to wear a mask when going to and when leaving the testing center. Anyone traveling with you will need to bring one.
What do you expect?
To conduct an antibody test for COVID-19, healthcare professionals will typically take a blood sample, usually through finger prick or venous aspiration from the hand. The sample will then be tested in a laboratory to determine whether or not you have developed antibodies against the COVID-19 virus.
COVID-19 antibody tests can give same-day results on some websites. Elsewhere, if the sample has been sent to the laboratory for analysis, the results may be available in a few days.
Results of antibodies to the COVID-19 virus can:
+ Positive: A positive result means you already have COVID-19 antibodies in your blood, indicating you’ve had the virus. It is also possible for you to test positive even if you have not had symptoms of a previous COVID-19 infection. False positive results may occur. There are cases where re-testing detects antibodies to the coronavirus that are “closely related” to COVID-19 or the quality of the test is flawed.
+ Negative: A negative result means you don’t have antibodies to COVID-19, so you probably haven’t had the virus before. Because these antibodies take time to develop, false-negative results can occur if your doctor takes the bood sample too soon after the infection has started.
People who have previously had the COVID-19 virus or tested positive for antibodies should not assume they are fully protected from re-infection with COVID-19. Researchers are trying to determine whether these antibodies actually provide immunity to the COVID-19 virus, if so, how much protection and how long they last. .
Even if your test results show you have antibodies to COVID-19, continue to take precautions such as wearing a mask in public, washing your hands regularly and practice social distancing – to avoid the risk of spreading the virus.
Explore Mayo Clinic’s research into new therapies, interventions and tests as a way to prevent, detect, cure or manage this condition.
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