Busted! The 4 biggest myths about COVID-19 antibody testing

Dr. Madelyn Fernstrom, NBC News’ health editor, separates fact from fiction.
A healthcare worker holds a vial with a blood sample while performing antibody tests for SARS-CoV-2 at the SklifLab laboratory of the Sklifosovsky Research Institute of Emergency Care on May 29, 2020, in Moscow.
Any influence of blood type on COVID-19 appears small compared with the substantial impact of known risk factors, such as older age and underlying health conditions, doctors say.Sergei Karpukhin / TASS via Getty Images

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By Madelyn Fernstrom, PhD

A lot of scientific brain power and research dollars are being going to tests and treatments for the novel coronavirus. And much recent attention has been focused on “antibody testing.” There’s a lot of excitement, because the presence of antibodies in your blood can reveal if you’ve been infected previously with the virus and produced an immune response to fight it off. But beyond that basic finding, there’s not much scientific evidence to translate what this means to your own health, as well as others.

Before I bust the biggest myths about the testing, it’s important to know exactly what antibodies are. They’re proteins produced by the body that recognize and bind to a virus. Once this happens, a process is triggered, which inactivates the virus and eliminates it from the body. This is the body’s natural immune response to a viral infection.

And while the field of immunology and antibody response has been studied for decades and is well-defined for many viruses (like polio), when it comes to COVID-19, the whole process is not well understood because it’s a never-seen-before virus.

So before you consider going for a COVID-19 antibody test, it’s time to do a little myth-busting to first understand what your results actually can tell you. Remember to always talk with your doctor for personal guidance.

MYTH #1: All antibody tests provide reliable information

Fact: Only a fraction of the tests advertised meet FDA specifications. At first, the FDA didn’t require manufacturers to get authorization from the agency, making test quality very inconsistent. But this changed on May 4, when the FDA announced that all companies had to submit validation data and apply for “emergency utilization authority” (EUA) to sell a test. Fewer than 20 of the dozens of tests available have achieved that so far. Always look for a test that documents accuracy of at least 99 percent, and ideally 99.5 percent. The FDA lists this information on their website.

MYTH #2: All antibody tests measure the same thing

Fact: Different tests measure different types of antibodies, with some more specific than others. A positive test only indicates that you were infected at some point in the past.

The typical “first responder” antibody of the immune system is called IgM (immunoglobulin M). Another type, IgA, found in the lining of the respiratory and digestive tracts contributes to the early response. The body next produces IgG (immunoglobulin G), an antibody better able to recognize and target a specific virus. The IgM component typically disappear after a few months, while the IgG lasts longer, and is likely the most useful measure for longer term immunity.

Only the small number of antibody tests receiving EUA authorization from the FDA are reliable, as they are at least 99 percent accurate and specific for particular antibodies directed against COVID-19. Some tests are measuring other kinds of viral antibodies.

Otherwise, you are open to a greater likelihood of a result that is a false positive (you really DON’T have antibodies) or a false negative (you really DO have them). Either “false” result doesn’t help make informed health decisions.

MYTH #3: If you have antibodies, you are protected from getting the virus again

Fact: There is no evidence that a positive antibody test protects you from another infection.With the presence of antibodies, there is some protection, but there’s still no information on how long that protection lasts and what level of antibodies you need to get that protection. A reliable antibody test only indicates if your body has produced antibodies to a previous infection. It also does NOT tell you if you have an active infection.

MYTH #4: You can go to your doctor’s office for a test

Fact: An antibody test cannot be done at a doctor’s office. You need to go to a large laboratory chain like Quest Diagnostics or LabCorp. And you can request the test via your primary care doctor, or schedule it directly. It’s important to check with your insurance carrier for coverage.

And remember that this is a blood test, with a scheduled blood draw at the lab. While there is a home test available, using a pin-prick blood test, the accuracy is uncertain and not recommended at this time.

Madelyn Fernstrom, PhD is NBC News’ health editor. Follow her on Twitter @drfernstrom.