Antibody Tests Are Everywhere Now and Confusing Everyone

(Bloomberg Businessweek) -- In mid-March, as the novel coronavirus spread across Europe and the U.S., Eve went with some friends to a London pub to mourn a ski trip the accelerating pandemic had canceled. They shared food and drinks, a last hurrah before the world went into lockdown.

The next day, Eve hopped on a plane to Dubai, where she stayed for a few days, then another to San Francisco. On March 28, after eating a blue cheese and truffle omelet that tasted like nothing, Eve tested positive for Covid-19. Eventually, so did most of her friends from the pub that night.

So she was surprised, to say the least, when two separate tests in early May told her she didn’t have antibodies to SARS-CoV-2, the virus that causes the disease. On May 15, another test confirmed she did in fact have antibodies to the virus. “It was confusing,” says Eve, who asked her last name not be published for privacy reasons. “There are no answers.”

She’s right. Yet antibody tests for Covid-19 are suddenly everywhere. Doctors are blasting out texts and emails urging patients to “book an antibody test today.” Botox clinics, flotation spas, and chiropractors have even gotten in on the act.

Test takers are seeking certainty, wanting to know if that bad flu they had in February was actually Covid-19—and whether that means they’re at lower risk of getting it again. But antibody tests, which hunt for signs in a person’s blood that they’ve been exposed, provide little if any actionable information. Many have been plagued by questions about their accuracy. And even if a test is accurate, experts have no solid proof that antibodies mean a person is immune to the virus, or good data on how long that immunity might last. Some people “mistakenly view antibodies as a get-out-of-jail-free card to return to normal life, a dangerous misconception,” Raja Krishnamoorthi (D-Ill.), chairman of the House subcommittee on economic and consumer policy, told a virtual hearing earlier this month. The subcommittee estimates that millions of people have taken the tests.

Caesar Djavaherian, the co-founder and medical director of Carbon Health Medical Group Inc., the chain of clinics that tested Eve, says that antibody tests present a conundrum for health-care providers. “We’re worried people will get a positive test and go about their business thinking they have immunity to the virus,” he says. “We actually considered not offering them at all. The only thing worse than no data is bad data.” Instead, Carbon Health decided to supply the test with a long list of caveats.

San Francisco-based primary care provider One Medical Group Inc. has devoted an entire team to vetting antibody tests. Chief Medical Officer Andrew Diamond says the company decided to offer them only after it was satisfied the ones it planned to provide were sufficiently accurate and that clinicians had been educated about their limitations. Diamond says he hopes the tests make people more cautious, not less. “Most people end up with a negative test,” he says. “The number of people who think they’ve had it is far greater than the number who actually had it. Those people do change their behavior. They say, ‘You know what, I should take this more seriously. I was getting cavalier out there, but now I’m going to wash my darn hands and wear this mask.’ ”

Not every clinic has been so considered in its approach. One Bloomberg employee in New York City recently received repeated text messages from companies called Manhattan Cardiology and Medical Offices of Manhattan, which also advertise the tests prominently online. It turns out the tests offered, from Diazyme Laboratories Inc., haven’t yet been authorized by the U.S. Food and Drug Administration. The results arrive with a list of caveats, including a warning that they shouldn’t be used as the sole data point to confirm an infection. Diazyme Managing Director Chong Yuan defends the accuracy of the company’s test but acknowledges it’s not necessary for most people to take it. A spokesman for Manhattan Cardiology and Medical Offices of Manhattan declined to comment.

Initially, the FDA didn’t require tests to get any government signoff before coming to market. The agency introduced stricter oversight in May, after questions arose about accuracy and claims made by some manufacturers. So far, just 18 tests have received formal emergency-use authorization. But the FDA has allowed almost 200 to remain for sale, including Diazyme’s, as they await review.

Patrick Hsu, an assistant professor of bioengineering at the University of California at Berkeley, was a senior author on a recent study on the accuracy of antibody tests. His group analyzed 14 tests and found only three produced consistently reliable results. “People want answers: Am I immune? Can I go back to work? Can I play soccer in the park?” Hsu says. “But the story’s not quite so simple.” He says that even for tests that can accurately detect the virus, many questions remain. A crucial mystery: If antibodies protect someone from getting the virus again, do they also prevent her from spreading it to other people?

For Eve, the negative test result was confusing. She’d clearly had the virus, but with only mild symptoms, and she worried her body hadn’t generated an immune response. The positive test, days later, allayed those concerns. Eve has since flown back to London, where she’s in graduate school. She admits she thinks of her fellow Covid-19 friends as her “immune herd.” After her testing experience, she says, “I am probably a bit less careful than I would be having not had the virus.”

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