By monitoring the body's molecular response to a viral attack, the new method developed by Flatiron Institute researchers and their colleagues can diagnose even asymptomatic patients with 98.4 percent accuracy.

By inspecting the body's immune response at a molecular level, a research team has developed a new way to test patients for COVID-19. Their method can potentially catch infections a matter of hours after exposure — far earlier than current COVID-19 tests can detect the virus — with near-perfect accuracy. The team describes their innovation, which is still in the early stages of development, in the February 27 issue of the journal Cell Reports Methods.

Most existing COVID-19 tests "rely on the same principle, which is that you have accumulated a detectable amount of viral material, for example, in your nose," says study lead author Frank Zhang, who worked on the project as a Flatiron research fellow at the Flatiron Institute's Center for Computational Biology (CCB) in New York City. "That poses a challenge when it's early in the infection time window and you haven't accumulated a lot of viral material, or you're asymptomatic."

When put to the test using real-world blood samples, the new method yielded an impressive 98.4 percent accuracy rating. That's especially impressive as the approach works just as well on asymptomatic patients, for whom rapid antigen tests can be less than 60 percent accurate. "It was really surprising that it worked so well," says Zhang, now an assistant professor at Cedars-Sinai Medical Center in Los Angeles. "It's a promising alternative and complementary approach to conventional PCR tests."

The new approach isn't ready for prime time yet, Zhang says. He and his colleagues only tested blood samples rather than the nasal samples that are more common and convenient for diagnosing COVID-19. Also, they need to make sure they can distinguish between the body's reaction to COVID-19 and its response to infections caused by other viruses, such as colds.

The researchers say they're optimistic, though, as other research groups have already made progress on tests that look solely at which genes turn on. Those same tests could easily add the mRNA analysis developed in the new study, thereby producing even better results, Zhang says. "Anything they can do, we can probably explore and join forces on," including catching cases within hours of initial exposure.