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Experts are racing to develop tests that can identify who has recovered from COVID-19 and may be immune. These serological tests search for coronavirus antibodies in the blood.
Such tests provide quicker results and are easier to produce than the diagnostic tests that help doctors identify positive cases.
A serological test that provides results within 15 minutes after a finger prick will be available within weeks in the US. It could help get immune Americans back to work and school.
Blood from recovered people could also be used to treat critically ill coronavirus patients.
It's easy to wonder whether the illness you had a few weeks ago was the coronavirus, though you might not have realized it at the time.
A new serological test could provide some clarity.
The test uses a few drops of your blood to determine whether you have antibodies for the coronavirus. If so, that means you got the virus and recovered from it (even if you never received a positive diagnosis).
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Having identifiable coronavirus antibodies in your bloodstream also means you've probably built up immunity. In an interview last week, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said he was confident that recovered coronavirus patients would be immune.
Fauci said he'd be "willing to bet anything that people who recover are really protected against reinfection."
That's why identifying people who had the virus and recovered is imperative in the fight against the outbreak — those people could return to work or school safely while others remain isolated.
"Ultimately, this might help us figure out who can get the country back to normal," Florian Krammer, a professor in vaccinology at Mount Sinai's Icahn School of Medicine, told Reuters. "People who are immune could be the first people to go back to normal life and start everything up again."
Coronavirus antibody tests are already widely in use in China and South Korea. In the US, many are in the works from various university labs and private companies. On Tuesday, the US Food and Drug Administration granted an Emergency Use Authorization for an antibody test from the medical company Bodysphere Inc.
According to a press release, millions of the "two-minute testing kits" could be in hospitals within weeks.
How the blood tests work
Antibody tests are different from the typical diagnostic tests used to determine whether someone has COVID-19. The latter involves taking samples of mucus and saliva and running a test in a lab to see if those samples contain the coronavirus' genomic sequence. That tells doctors whether the patient has an active infection, and the test results can take 24 to 48 hours.
A serological test, on the other hand, can tell whether a person has coronavirus antibodies in 10 to 15 minutes. The tests surface letter bands to indicate the results, similar to the way home pregnancy tests work.
"They either detect human antibodies in blood using an antigen designed to be similar to a feature of the virus," Charles Cairns, the dean of the Drexel University College of Medicine, told Science News. "Or conversely, the test detects the virus in blood using a [human-made] antibody designed to trap the virus."
An at-home kit would include a needle to prick your finger with, a 3-inch mixing stick, and a test solution, according to David Ho, the CEO of the Aaron Diamond AIDS Research Center.
Antibody blood tests have been used for about two decades in other disease-tracking initiatives, including for HIV in rural Africa, Ho said in a video call sponsored by the group Committee of 100. The kits cost $1 to $6 each, he added, depending on the volume purchased.
Identifying who's immune to the coronavirus could help get people back to work sooner
Some US companies are already selling antibody tests to other countries. The California biotech company Biomerica sells COVID-19 antibody tests for less than $10 in Europe and the Middle East, according to Reuters. Chembio Diagnostics, a medical-device company based in New York, is sending its antibody tests to Brazil and plans to study them in the US, Reuters reported.
In Colorado, United Biomedical is working with one county to test 8,000 residents for COVID-19 antibodies. And Henry Schein Inc. has begun manufacturing "several hundred thousand" point-of-care antibody tests and expects "significantly increased availability" in the month ahead.
The UK government bought 3.5 million at-home antibody tests last week, according to The Guardian, and is looking to distribute them to people who are self-isolating as soon as possible.
Researchers at Germany's Helmholtz Centre for Infection Research in Braunschweig want to send out hundreds of thousands of antibody tests to residents over the coming weeks, Der Spiegel reported on Friday. Germany might even issue "immunity certificates" based on the results.
William Schaffner, a professor of infectious diseases at the Vanderbilt University School of Medicine, told Reuters that serological tests were appealing to political and business leaders alike.
"These tests would be very attractive if they're cost-effective, readily available, and easy to do," he said.
Blood from people who've recovered from COVID-19 could help treat others
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Coronavirus antibodies from the bloodstreams of people who have recovered could also help patients who are actively fighting infections.
Last week, the FDA approved the emergency use of an experimental treatment that uses blood from people who've recovered from the coronavirus. This type of transfusion, which dates back to the Spanish flu outbreak of 1918, is based on the transfer of antibodies from person to person.
The approach shows promise: Five critically ill coronavirus patients in China got better after receiving plasma transfusions from patients who had previous coronavirus infections.
New York Gov. Andrew Cuomo said last week that the state planned to start using the plasma treatment for its COVID-19 patients.
Ben Pimentel contributed reporting.