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An at-home fingerprick blood test may help detect your exposure to coronavirus

If approved, the blood test could show if your immune system has developed coronavirus antibodies. But a positive result isn't a license to return to work.

Americans may soon be able to learn if they've ever been infected with COVID-19 with a prick of their finger and a smartphone — and without having to leave their homes.

A Los Angeles digital healthcare company called Scanwell Health is seeking U.S. government clearance for a kit that lets users submit a scanned image of a blood test to doctors via their phones. Within a few hours, according to the company, the user will learn whether the blood contains antibodies for coronavirus.

"The entire testing process happens at home," says Scanwell Chief Medical Officer Jack Jeng, "No specimen has to be shipped back."

A positive test result means a patient has been exposed to COVID-19 at some point in the past and has developed antibodies to fight it.

"The Scanwell rapid serology test is looking for antibodies in the blood. A positive test result means that you were exposed to the virus previously because it takes time for the antibodies to develop," said Jeng.

David Kroll, a professor of pharmacology at the University of Colorado who has worked on antibody testing, explained that the antibodies mean "your immune system [has] remembered the virus to the point that it makes these antibodies that could inactivate any future viral infections."

What the test can't do is tell you whether you're currently sick with coronavirus, whether you're contagious, whether you're fully immune — and whether you're safe to go back out in public.

Because the test can’t be used as a diagnostic test, it would need to be combined with other information to determine if a person is sick with COVID-19.

"However, when combined with symptoms consistent with COVID-19 like a fever, cough, and sore throat, a positive test is pretty much diagnostic for the illness," said Jeng, "That is how these rapid serology tests are being used in China."

Scanwell's serological test is not a treatment. Other companies are developing antibody treatments in which blood plasma of people who've recovered from COVID-19 is used to treat sick patients with the virus.

Other companies, including LabCorp and Quest, are also developing tests to detect antibodies, but those are intended for hospital and lab use. On Thursday, the FDA issued its first Emergency Use Authorization for a rapid antibody blood test developed by Cellex for use in laboratories.

The Scanwell test is also different from the diagnostic throat and nasal swab tests for coronavirus that are currently in use. Known as PCR tests, they detect the virus's genetic material. "The serological test is more of a history book, it tells you whether a person has been exposed to the virus," says Kroll.

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The test kits are manufactured by Innovita, a Beijing biotech company, that has an exclusive three-year U.S. partnership with Scanwell. Innovita, which Jeng says has the capacity to produce 500,000 kits a day, has distributed tests in China, Iran, and the Czech Republic.

The tests have been approved by the Chinese version of the Food and Drug Administration, but for use in the U.S. they will have to cleared by the FDA. Scanwell has applied to the FDA for Emergency Use Authorization, and the earliest the approval would come would likely be two months from now, according to Jeng.

How the tests work

Once a doctor from Scanwell partner telehealth company Lemonaid determines a patient's eligibility for the test, the test kit is sent via next business day delivery to the patient's home, said Jeng. The patient places the blood droplet on a test cassette. After 15 minutes, the results appear and the patient uploads an image to the Scanwell Health app. On the other end, a Lemonaid doctor or nurse practitioner will deliver the results in a few hours, said Jeng.

"If they are infected, by not leaving the house they are not exposing others to the infection," said Jeng. "If they're not infected, they're not being exposed to others in a waiting room who may have the infection."

Scanwell, which is best known for creating the first at-home smartphone-enabled UTI test cleared by the FDA, received its first shipment of 200 coronavirus test kits from Innovita last week and is expecting 10,000 more later this week. Labs across the country will begin testing the kits with blood from patients who've been confirmed to have COVID-19.

In response to the COVID-19 outbreak, Lemonaid and Scanwell are working together to develop and distribute a test for at-home use.Scanwell

Testing too soon

In the detection of the virus that causes COVID-19, timing is critical. A negative result may be negative simply because the immune system hasn't had time to develop antibodies.

"[If] you test too soon, you could be negative," said Elitza S. Theel, director of the Infectious Diseases Serology Lab at the Mayo Clinic in Rochester, Minnesota. "Most individuals become positive for these antibodies about 14 days or after symptom onset or infection."

"If you're positive, you probably have some level of protective immunity. But frankly, we don't know how long that lasts at this point."

As far as being contagious, Theel says for those who test positive for antibodies, "[W]e cannot determine at this point based on a serology test whether or not you're infectious. If you're still symptomatic and early after your symptom onset, you may still very well be transmitting virus."

"On the other hand, you know if you're 20, 30 days out, post symptom onset, you're no longer symptomatic and you're antibody positive, chances are then you're probably not transmitting virus."

New York Gov. Andrew Cuomo is banking on antibody tests to identify individuals who've developed immunity to help restart the economy, "That would be very important for us to know because then healthcare workers that could go back to work," said Cuomo, "there are workers that could return back to the private sector."

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Kroll warned, however, that a positive test doesn't mean a quick return to the workplace. "I do think it'll be part of our return to work," said Kroll. "[But] we're not going to be stay at home one day and then the next day everybody's allowed to go out."

Jeng himself has a conservative take about an immediate return to the workforce. He said antibody tests are only one piece of the diagnostic puzzle. "Thinking that you're completely immune," he said, "may put you at risk."

Jeng is also an anesthesiologist at the University of California-San Francisco Medical Center. He often performs procedures like placing breathing tubing in patients, a very high risk procedure if that patient has the coronavirus.

"If I had antibodies, and I knew I had antibodies to the virus, I'm still going to wear my personal protective equipment," says Jeng, "So I would volunteer to take care of our sickest and most high-risk patients. And I would not want my colleagues who do not have any antibodies to be the ones doing this kind of risky procedure."

"Regardless of your immune status, you should still do the right thing and protect yourself," said Jeng.