COVID-19 immunity tests in the works — but none accurate enough to roll out yet, official says

Chicago’s top public health official on Monday explained that testing for immunity is still flawed because tests can currently return results that are both falsely negative and falsely positive.

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A test for COVID-19, also known as SARS-CoV-2.

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Chicago’s top public health official warned Monday that antibody testing used to screen for immunity to the novel coronavirus remains unreliable and that an accurate test may not be approved for weeks.

During a question-and-answer session posted on social media, Dr. Allison Arwady explained that testing for immunity to get an indication of infection at a “population level” is still flawed. That’s because the blood tests can currently return results that are both falsely negative and falsely positive, said Arwady, the commissioner of the Chicago Department of Public Health.

While the Food and Drug Administration has granted Emergency Use Authorization to a test developed by North Carolina-based Cellex, FDA Commissioner Stephen Hahn warned Sunday that antibody tests being reviewed by the agency “may not be as accurate as we’d like them to be.

“No test is 100% perfect, but what we don’t want are wildly inaccurate tests. That’s going to be much worse, having wildly inaccurate tests, than having no tests,” Hahn said on “Meet the Press.”

Gov. J.B. Pritzker and Mayor Lori Lightfoot have recently said that widespread COVID-19 testing is necessary to get the city and state back up and running, though officials are erring on the side of caution when it comes to antibody tests. Arwady said officials in Chicago are only utilizing antibody tests in conjunction with testing for the virus, while the governor’s office is waiting to validate antibody tests that have been ordered.

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Dr. Allison Arwady the Commissioner of the Chicago Department of Public Health

Tyler LaRiviere/Sun-Times

Accuracy only at 60%

“Our experts aren’t quite comfortable with their accuracy rates that hover around 60%,” said Jordan Abudayyeh, a spokeswoman for the governor. “Until IDPH can ensure the tests provide accurate data, we will not deploy them in a widespread way.”

Though antibody testing could be informative for authorities trying to determine when to lift orders that have shut down many businesses and forced people to remain at home for weeks, Arwady said it’s still unclear how long antibodies to the deadly virus last and whether people can develop complete or just partial immunity.

Tests could also falsely come back negative, meaning a person infected with COVID-19 might not test positive for those antibodies, which she said “take even longer to show up than the virus does.

“So you actually have to wait a certain number of days before you would even trust an antibody test at all,” she said. “It’s fine if you think you had symptoms in February or March and you didn’t get tested. We’ll be able to test you later once there is a full FDA-approved test.”

What’s more, Arwady said, the tests can also return falsely positive results because COVID-19 “is just one in a family of coronaviruses” that also includes MERS and SARS. She noted that around 10-15% of colds are caused by innocuous coronaviruses, which can’t yet be distinguished from COVID-19 using current antibody tests.

“So you could go and get an antibody test and say, ‘Oh, I’m fine, right? I must have had COVID-19 and I’m sort of good to go,’” said Arwady. “No, … you might have had the common cold that wasn’t COVID-19 and you could have this false sense of security. I don’t want people yet using these antibody tests before they’ve been validated.”

Once that’s happened, Abudayyeh said the tests will be used by the state “as another tool to study the virus and collect data.” However, that could take a couple weeks in Arwady’s estimation.

“I know everybody’s really anxious,” she said. “Trust me, I’m one of the most anxious to have a validated antibody test that will help us understand some of this at a population level. But there still are some limitations just right now.”

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