Researchers Study Accuracy of Available COVID-19 Antibody Tests
An initiative started by scientists at both UC San Francisco and UC Berkeley to study antibody test kits may help doctors and public health officials decide which tests are reliable enough for public use.
Currently, there are more than 120 antibody test kits available, and only a handful of these antibody test kits have received Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA).
When the body is infected with a virus like SARS-Cov-2, the cause of COVID-19, the body produces an antibody called IgM in an effort to neutralize the virus generally. Later, as IgM levels go down, the body begins to increase production of a different antibody called IgG for more specific targeting. As the United States moves toward opening its economy, reliable testing of antibodies like these can help determine who has already been infected with COVID-19.
Each of the 12 test kits studied thus far was used against about 300 blood samples, some with SARS-Cov-2 and some without. Results from the first dozen tests reveals that testing works best at least two weeks or more after infection. Some kits also have high false positive rates that need to be examined further. The team has submitted these findings for publication and has expanded the number of tests they are evaluating. They are also sampling blood from patients who have fully recovered from COVID-19 to see how long antibodies stay in the body.
"Several of our tests had specificities over 98 percent, which is critical for reopening society," said Patrick Hsu, Ph.D., an assistant professor of bioengineering at UC Berkeley, in a press release about the project. Specificity is a measure of how good a test distinguishes infected people from those who are not. A high specificity means a low false positive rate.
The researchers said that additional critical information is still required before assuming that antibody tests can safely predict protection from future infections.