For the past few weeks, more than 50 scientists have been working diligently to do something that the Food and Drug Administration mostly has not: Verifying that 14 coronavirus antibody tests now on the market actually deliver accurate results.
These tests are crucial to reopening the economy, but public health experts have raised urgent concerns about their quality. The new research, completed just days ago and posted online Friday, confirmed some of those fears: Of the 14 tests, only three delivered consistently reliable results. Even the best had some flaws.
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In the new research, researchers found that only one of the tests never delivered a so-called false positive — that is, it never mistakenly signaled antibodies in people who did not have them.
Two other tests did not deliver false-positive results 99 percent of the time.
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Four of the tests produced false-positive rates ranging from 11 percent to 16 percent; many of the rest hovered around 5 percent.
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The team began with a modified version of the method Dr. Whitman had devised to validate Chagas tests. The researchers created a biosafety-certified space, obtained the needed approvals and procured hundreds of blood samples from two Bay Area hospitals.
They also purchased tests from Chinese manufacturers, clearing customs regulations and sometimes accepting Uber deliveries in the middle of the night. In all, the investigators analyzed 10 rapid tests that deliver a yes-no signal for antibodies, and two tests using a lab technique known as Elisa that indicate the amount of antibodies present and are generally considered to be more reliable.
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New tests also usually compete with an established gold standard. Lacking such a standard, the team instead compared all the tests in a “head-to-head bake-off to see who’s the winner,” Dr. Hsu said.
Each test was evaluated with the same set of blood samples: from 80 people known to be infected with the coronavirus, at different points after infection; 108 samples donated before the pandemic; and 52 samples from people who were positive for other viral infections but had tested negative for SARS-CoV-2.
Tests made by Sure Biotech and Wondfo Biotech, along with an in-house Elisa test, produced the fewest false positives.
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Dr. Marson and his colleagues have acquired tests from nearly 100 manufacturers, and plan to continue comparing them. The scientists also hope to expand their sample set to include people who were mildly ill or did not feel ill at all, and to stratify their data by age and the presence of chronic conditions.
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