Coronavirus antibody tests may give false positives, says new research

A recently released report has raised questions over antibody test that checks for prior COVID-19 infection, citing they had high rates of false positives in screenings performed by a consortium of California laboratories.

A false positive is a potential danger as people could then think they were immune to the virus when they're actually still vulnerable.

Of the 12 antibody tests that were studied by the COVID-19 Testing Project, one of the tests gave false positives more than 15% of the time. Three other tests gave false positives more than 10% of the time.

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According to experts, their false positive rates should be 5% or lower, or ideally 2% or lower.

A good antibody testing is critical to getting back to normal, since they might help assess who in the US has immunity. That's why the false positives are so dangerous.

The COVID-19 Testing Project is a consortium of researchers and physicians at the University of California San Francisco, the University of California Berkeley, the Chan Zuckerberg Biohub, and the Innovative Genomics Institute.

The faulty tests have their root cause in the guidelines and the relaxation given for them. In mid-March, when it became clear that COVID-19 was starting to whirl out of control, the FDA allowed companies to sell tests without first providing evidence that they worked.
Some 175 test developers took advantage of these new rules and could legally market their antibody tests without first having their validation data evaluated by the FDA, a professor of epidemiology and biostatistics at UCSF School of Medicine said.

The California researchers obtained as many tests as possible, but so far have been unable to screen antibody tests by large test makers such as Roche and Abbott, because they require proprietary instruments to run the tests, which the California tests did not have.