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State health official warns of COVID-19 antibody testing dangers

If you want to get an antibody test for COVID-19, this is what you should know before paying for the test.

AUSTIN, Texas — State and local health officials are sounding the alarm on COVID-19 antibody tests that are gaining popularity in Central Texas.

A serological test, which is more commonly known as an antibody test, measures the antibodies in your blood to help determine if you’ve ever been infected with COVID-19.

The tests are good at telling whether a person has been affected and if their body mounted an immune response, said Dr. Jennifer Shuford, the infectious disease medical officer at the Texas Department of State Health Services.

According to the FDA, "the test detects the body’s immune response to the infection caused by the virus rather than detecting the virus itself."

But so far, the FDA has only given emergency use authorization to one company, Cellex, for antibody testing.

“[The FDA has] looked at the data, but they're not as confident in the performance of that test,” Dr. Shuford said. “It's good enough that they'll allow it to be used under emergency in an emergency situation.”

That’s the minimum threshold though, Dr. Shuford said, that a consumer should know before paying for an antibody test.

“Consumers should expect at least that level of vetting or at least that level of confidence in their test that they are going to take to that they know that results mean something,” Dr. Shuford said.

More than 70 test developers told the FDA they have serological tests available, and other test manufacturers and laboratories have notified the FDA that they have validated and are offering serology tests – but none of them have received FDA emergency authorization.

"Some firms are falsely claiming that their serological tests are FDA approved or authorized, or falsely claiming that they can diagnose COVID-19. The FDA will take appropriate action against firms making false claims or marketing tests that are not accurate and reliable," the FDA said in a statement.

The FDA is allowing those tests to proceed, but only if test results include the following:

  • Notice that the test was not reviewed by the FDA
  • Notice that negative results do not rule out infection, especially in those who have been in contact with the virus
  • Notice that results should not be used as the only basis for diagnosis
  • Notice that positive results may be due to past or present infection with a different coronavirus strain

“When there's a test being used that hasn't been evaluated at all by the FDA, we have concerns that there might be more false positives or more false negatives using those tests,” Dr. Shuford said.

Austin Public Health told KVUE in a statement, in part: “Those interested in obtaining an antibody test that is not FDA approved are taking a risk with the accuracy of the test."


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The accuracy of the tests also was analyzed by Austin-Travis County Deputy Medical Director Dr. Jason Pickett on a recent podcast. By taking the test too early, it could be less accurate.

“It takes at least five days and often a lot longer, like 12 days or longer, for that to show up in sufficient quantities to where it can be reliably shown on a test,” Dr. Pickett said on the podcast.

The results of the test also shouldn’t change social distancing or quarantine behaviors, he said.

Dr. Shuford recommended asking your health care provider before paying for an antibody test if it’s authorized by the FDA. 

If it isn’t authorized, you can still get tested, but also realize that negative results don’t fully rule out COVID-19 infection, she said.

“This virus is so new that we're still seeing how people's immune response actually develops to this infection,” Dr. Shuford said.

There’s a lot of potential for antibody testing, Dr. Shuford said, which could eventually help determine when people can return to work or be out in the community.

WATCH: Austin clinic offering COVID-19 antibody testing


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