DARPA-led early COVID-19 detection test a week away from EUA submission

Scientists working for the US military have designed a new COVID-19 test that could potentially identify carriers before they become infectious and spread the disease, according to the Guardian.

In what could be a significant breakthrough, project coordinators hope the blood-based test will be able to detect the virus’s presence as early as 24 hours after infection – before people show symptoms, and several days before a carrier is considered capable of spreading it to other people. That is also around four days before current tests can detect the virus.

The test has emerged from a project set up by the US military’s Defense Advanced Research Projects Agency (DARPA) aimed at rapid diagnosis of germ or chemical warfare poisoning. It was hurriedly repurposed when the pandemic broke out and the new test is expected to be put forward for emergency use approval (EUA) by the US Food and Drug Administration (FDA) within a week.

“The concept fills a diagnostic gap worldwide,” the head of DARPA’s biological technologies office, Dr Brad Ringeisen, told the Guardian, since it should also fill in testing gaps at later stages of the infection. If given FDA approval, he said, it had the potential to be “absolutely a gamechanger”.

While pre-infectious detection would improve the efficiency of test-and-trace programs as governments worldwide relax lockdowns, DARPA cautioned that it must wait until after FDA approval is given and the test can be put into practice for evidence of exactly how early it can pick up the virus.

Prof Stuart Sealfon, who leads the research team at Mount Sinai hospital in New York, said the testing approach, which looks at the body’s response as it fights Covid-19, should produce earlier results than current nose-swab tests that hunt for the virus itself.

The research behind the development of the tests will eventually be made public, with the collaborating teams from medical schools at Mount Sinai, Duke University, and Princeton University expected to publish online, allowing scientists around the world to trial similar methods.

If EUA is granted, the test should start being rolled out in the US in the second half of May. Approval is not guaranteed, but DARPA scientists are enthusiastic about the potential impact as governments loosen lockdowns amid worries about controlling potential second-wave outbreaks.

“We are all extremely excited. We want to roll this test out as quickly as we can, but at the same time share with others who might want to implement in their own countries,” said Dr Eric Van Gieson, who set up DARPA’s epigenetic characterization and observation (ECHO) program last year to diagnose biological warfare victims and has redirected it to focus on COVID-19.

Hope that the test might pick up carriers before they become infectious is based on previous research into other viruses, though it remains unclear whether the same is true for COVID-19.

“We have evidence that diagnosis happens in the first 24 hours for influenza and an adenovirus,” Van Gieson said. “We are still in the midst of proving that with COVID-19. That said, we should know very soon after EUA.”

He sees potential for the US to carry out up to a million tests a day, starting with 100,000 daily in May. The test would up up the possibility of isolating pre-infectious cases and closing down transmission chains. It could also dramatically reduce quarantine periods for people exposed to Covid-19 spreaders, allowing them to go back to work within days.

“It could have exceptional demand,” said Chris Linthwaite, the chief executive of Fluidigm, a California life-sciences technology company that is part of the project, who believes frequent testing can help manage workforces as they return to offices, warehouses and factories.

The test uses the same polymerase chain reaction (PCR) machines used for checking nasal swabs from people suspected of having the virus.

“It’s a simple tweak,” said Van Gieson. “The infrastructure is already there.”

Limitations on use depend on PCR capacity, stocks of chemical reagents and logistics. Results can take an hour, or longer if samples must be sent away to laboratories. Blood samples are harder to collect than nose swabs, but may be more reliable. Swab testing can be difficult because it requires taking a sample from deep inside the nose.

Like the viral test, the new blood test hunts for RNA; in this case it is messenger RNA (mRNA).

“Target mRNA is part of the immune response to viral infection,” Sealfon said. “mRNA expression levels really do adjust due to the presence of COVID-19. Understanding the immune response is key to fighting COVID-19.”