| Antibody tests have been plagued by concerns of accuracy.
Such tests look for signals that a person’s body has encountered SARS-CoV-2, rather than hunting for the virus itself. But finding those signals is more complicated than simply diagnosing the disease.
On Monday, the White House acknowledged that complexity, suggesting that the U.S. should perhaps use two antibody tests at a time to gain a more accurate picture of how many people in the country have actually contracted the virus. In a document detailing the U.S. national strategy to expand testing efforts, the Trump administration said that the use of two tests at once would allow for the results to be checked against each other, producing, in theory, data that is more reliable.
An at-home Premier Biotech Inc. Covid-19 antibody rapid test cassette.
Photographer: Adam Glanzman/Bloomberg
“Highly specific and sensitive antibody tests will enable a better understanding of the spread of the virus and identify those who have already been infected,” the report said. “These tests, however, must be very accurate and reliable to guard against false positives, which can lead people to incorrectly believe they had the virus and may be immune from further infection.”
Antibody tests will be crucial to understanding how widespread the virus really is — and ultimately rolling back restrictions. But so far, there have been a lot of indications that existing tests have a lot of issues.
The few big antibody studies that have been done have attracted ample criticism and varied wildly in their findings. A Stanford University study of Santa Clara County, California, for example, concluded that about 4% of the population there had virus antibodies. A study by the state of New York found 21% of New York City residents had been exposed.
A high number of false positives could mean the virus isn’t quite as widespread, but also more deadly.—Kristen V. Brown. |