25 Investigates: Antibody tests are both promising and perplexing

Boston 25 News at 6:00 p.m.

BOSTON — 25 Investigates cameras were present last week when Lauren Nichols was heading to a lab in Brighton to get an antibody test.

The Boston resident and federal government employee tested positive for COVID-19 eight weeks earlier, but she wanted to get an antibody test to determine if she could donate plasma. So she paid for the test out of pocket and a day and a half later she got the results.

“The results of my test were negative, which was surprising to me,” said Nichols.

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Surprising because she knows she had the coronavirus. In fact, she has been battling COVID-19 symptoms on and off for more than 54 days.

Antibody testing does not look for the virus itself. Rather, it identifies antibodies, or proteins, the body creates to fight off the virus.

According to the Centers for Disease Control and Prevention (CDC), it can take between one and three weeks after infection to make those antibodies.

Nichols assumed two months would have been more than enough time for her body to produce antibodies.

“On a COVID test it would be great, but an antibody test it was really disappointing. So it's kind of hard to stomach. I didn't know what to make of it. It’s very confusing,” she said.

Nichols got her antibody test at a Quest Diagnostics lab. Quest uses tests authorized for emergency use by the Food and Drug Administration (FDA). More than 200 antibody tests have flooded the market in just the last few weeks, but only about a dozen have received Emergency Use Approval from the FDA.

25 Investigates contacted Quest Diagnostics and they offered a number of possibilities for the surprising results. Among the reasons: A patient did not develop an immune response to the virus, the antibody test was conducted “too soon after infection and the antibodies weren’t detectable,” and a false negative, meaning the test got it wrong.

The test’s reliability has been questioned by some scientists, while others say they should be used with caution.

“There is no perfect test which can be done. All of them have limitations,” said Dr. Richard Ellison, an infection disease specials at UMass Memorial in Worcester. “We’re still just in the beginning phases of understanding how to use the testing and getting really getting good testing available.”

According to Ellison, antibody testing is typically done by exposing blood or saliva to an inactive form of the virus and then checking for a reaction. But a test’s sensitivity and accuracy vary by the lab that makes them.

Scientists are still uncertain about how much protection against future infection people with antibodies have or how long that protection might last.

“I would say probably several different tests will eventually turn out to work well. The best thing we want to know is this: Does a test predict whether someone's immune to the virus? And that actually requires an even a more specialized test,” added Ellison.

Expert say antibody testing should not be used as a sole basis to diagnose or exclude infection.

The FDA is actively working with the CDC and several other agencies to independently validate antibody tests on the market right now.

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