What to know about the COVID-19 antibody test

Do you think you may have had COVID-19 and didn’t have any symptoms? It’s possible you caught the virus, known as SARS-CoV-2, and didn’t even know it.

While molecular COVID-19 testing for those who are experiencing symptoms is now available across the country, these tests only reveal if someone is currently infected. They do not indicate if someone has been infected in the past.

However, a new test that measures the presence of antibodies against the SARS-CoV-2 virus could be a “game-changer” in our fight against COVID-19. Antibody testing was recently granted under section IV.D of the U.S. Food and Drug Administration’s (FDA) Policy for Diagnostic Tests for Coronavirus Disease-2019.

To learn more about COVID-19 antibody testing, we spoke with Banner Health experts, Brian Mochon, Ph.D., a clinical microbiologist and system medical director of Sonora Quest Laboratories/Laboratory Sciences of Arizona for infectious disease testing, and James Utley, system blood bank technical director of Laboratory Sciences of Arizona.

What is a COVID-19 antibody test?

Antibody testing measures the development of immunoglobulins, otherwise known as antibodies, which are produced by your immune system. Your body makes antibodies when it fights off infections like COVID-19, or when you get a vaccine, such as a flu shot.

Your body makes different types of antibodies, such as immunoglobulin G (IgG), IgM or IgA. These antibodies, especially IgG, can last for a long time in your body after the infection has resolved. Antibody testing, also known as serology testing, can be used to identify which infections your body has been fighting.

“The COVID-19 antibody test looks for the presence of the SARS-CoV-2 IgG antibodies that may have developed after someone has been exposed to or been infected by the virus,” Dr. Mochon said. “The test may indicate that you’ve been exposed to the virus but have developed antibodies against it that may protect you from future infection.”

When should I get tested?

IgG antibodies typically develop between 10-14 days after symptom onset. If you’ve been exposed, diagnosed with or have recently recovered from COVID-19, speak with your health care provider on next steps regarding antibody testing.

Where can I get tested?

For some people, antibody testing might not be available yet, but every day cities and states across America are rolling out tests.

If you’ve tested positive for COVID-19 and have fully recovered (at least 10 days), contact your health care provider regarding antibody testing.

What if I haven’t tested positive for COVID-19? Can I still get tested?

As with most diagnostic tests, the performance characteristics of antibody testing were based on samples collected from patients diagnosed with COVID-19. Because of this, there is limited data on the effectiveness of this test in individuals who have previously tested negative for COVID-19 using molecular testing.

Will my insurance cover testing?

Antibody testing prices can vary, but some laboratories are not billing patients for this test when ordered by a physician. However, some private labs are offering antibody tests to the public, with or without a doctor’s referral, for a fee.

How are the results of the test interpreted?

“If an antibody test provides a positive result for the IgG antibody, it suggests the individual was previously exposed to SARS-CoV-2, which may indicate a prior infection that has resolved or is still resolving, and/or protection against re-infection (i.e., protective immunity),” Dr. Mochon said.

Your health care provider will work with you to determine the next steps you should take.

Why is the antibody test helpful?

According to a recent white paper summary issued by the American Clinical Laboratory Association, when used appropriately, antibody testing may help determine the number of people who’ve been infected with the virus.

The presences of these antibodies may aid in contact tracing and general population surveillance to pre-empt potential future outbreaks and establish “herd immunity” in populations.

“This antibody test is an important tool in assessing potential risk and fostering a safer environment for all of us,” Dr. Mochon said. “We look forward to additional science to establish clearly the role of antibody testing in inferring immunity for COVID-19. Other respiratory illnesses, including SARS, a cousin to COVID-19, have been shown to produce antibodies that can be accessed via lab testing to infer immune protection for a period of time.“

The antibody test may also help with an experimental treatment called convalescent plasma, a liquid found in your blood. Convalescent plasma is currently being evaluated as a potential treatment option for COVID-19 patients in an investigational format with the FDA.

“Convalescent plasma is donated from patients who have fully recovered from the virus,” Utley said. “COVID-19 patients produce antibodies located in the plasma directed against the SARS-CoV-2 virus. If you’ve fully recovered from the virus, you can volunteer to donate plasma at your local blood donation center.”