• A study backed by the Chan Zuckerberg Biohub found several companies are offering antibody tests for the novel coronavirus with less than 90 percent accuracy. 
  • The accuracy of the tests varies depending on how they’re used.
  • It’s the latest report to indicate that antibody kits with varying levels of accuracy are flooding the US healthcare system. 
  • Visit Business Insider’s homepage for more stories.

We just got our best look yet at the performance of tests designed to figure out whether people have had the novel coronavirus in the past.

A study backed by the Chan Zuckerberg Biohub, a medical research center founded by Facebook CEO Mark Zuckerberg and Dr. Priscilla Chan, reveals that several tests that detect antibodies for the novel coronavirus have less than 90 percent accuracy.

Antibody or “serology” tests find antibodies the body produces in order to fight off infection. They’re crucial to the country’s surveillance efforts, since they can detect past exposure to the coronavirus and fill gaps in our’ understanding of just how far it has spread.

In order to make coronavirus tests more widely available during the pandemic, the US Food and Drug Administration said that companies could sell them without official approval. Since then, dozens have flooded the market, creating fear among some experts that the kits could fall short of their claims.

Read more: Tests that can tell who’s had the coronavirus are crucial to reopening the country. Here are the companies racing to bring them to the US healthcare system.

The study compared 12 tests and found that their ability to correctly identify coronavirus antibodies varied widely. That measure, known as sensitivity, ranged from 81.8% to 100% after 21 days since the onset of coronavirus symptoms, according to the report. At least three companies’ tests had lower sensitivity than previously reported, according to the findings.

Authored by researchers at UCSF, UC Berkeley, Chan Zuckerberg Biohub, and Innovative Genomics Institute, the findings are preliminary and not peer-reviewed. 

Wide-ranging accuracy findings

Fewer than 300 samples were included in the final analysis. They came from patients with symptomatic infections and positive coronavirus diagnoses, or donated blood from the American Red Cross.

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Just 11 of the samples came from people who donated more than 20 days after the onset of their symptoms. That’s a big limitation, since antibody counts can increase over time as the body ramps up to fight off infection. Many of the tests had similar accuracy after the 20-day mark.

Tests from Sure Biotech, Premier Biotech, DeepBlue Medical Technology, Beijing Decombio Biotechnology, UCP Biosciences, and Epitope Diagnostics’ were all found to have 90.91% accuracy in a combined exam for IgM and IgG antibodies, two proteins made in the body’s immune response to COVID-19, the disease caused by the coronavirus.

The lowest performing tests after 20 days of symptoms were those by BioMedomics at 81.82% sensitivity, Innovita Biological Technology at 83.33%, and Guangzhou Wondfo Biotech at 81.82%. 

Henry Schein, one of the largest distributors of medical devices in the US, has a deal with BioMedomics to sell more than 1 million of the antibody kits to healthcare professionals over the coming months. The company did not respond to a request for comment.

Diagnostics companies GeneSystems and Scanwell Health have distribution agreements with Innovita. Jack Jeng, Scanwell’s chief medical officer, said the study evaluated an earlier version of Innovita’s antibody kit that’s now been improved. 

Scanwell is one of the few companies with ambitions to make serology kits available in people’s homes. Those tests face stricter FDA regulations.

“Based on their validation data, Innovita’s newer version should have better performance characteristics. We are validating the tests and will proceed based on those results,” Jeng said in a statement. 

Some bright spots

The tests generally didn’t confuse antibodies made to fight other viruses with COVID-19 antibodies. And they all exhibited greater than 95 percent accuracy when it came to identifying their absence, a metric called “specificity.” That means they tended not to report false positives. 

GeneSystems said in a statement that Innovita’s test was found to have 100% specificity for the IgG antibody, which can be just as important as sensitivity scores.

Researchers thought it was curious that more than three tests identified individuals who may have been incorrectly cleared by diagnostic tests after the onset of their coronavirus symptoms. That points to the potential of the tests to buffer normal testing, which is most sensitive during a brief window of time, according to the authors.

Several major healthcare companies, including Abbott Labs, Siemens Healthineers, and Roche are now making tens of millions of antibody tests each that were not included in the study. Analysts believe they could supply the US healthcare with enough accurate tests to meet demand, according to research this month by Morgan Stanley and SVB Leerink.

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