How A Coronavirus Blood Test Could Solve Some Medical Mysteries

Scientist lab testing.
The most common test for coronavirus infections checks for the virus' genetic material. A blood test that, instead, measures antibodies against the virus could give doctors and researchers more information. CREDIT: Jane Barlow /WPA Pool/Getty Images

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BY RICHARD HARRIS

As the coronavirus spreads more widely around the globe, scientists are starting to use a powerful new tool: a blood test that identifies people who have previously been exposed to the virus. This kind of test is still under development in the United States, but it has been rolled out for use in Singapore and China.

The current lab test used in the United States identifies people who are currently spreading the virus that causes COVID-19. That’s crucial information, but that test doesn’t reveal who had previously been infected. That’s important too for understanding the unfolding epidemic.

The other test, used widely in science and medicine, detects antibodies that people produce after they’ve become infected with a bacterium or virus. Those antibodies can appear in the blood one to three weeks after infection, and they’re part of the immune system’s response to infection.

The antibody-based tests can identify people who were not known to be infected “either because they never developed symptoms, or they had symptoms that were never correctly diagnosed,” says Lauren Ancel Meyers, a biology professor at the University of Texas at Austin.

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