Health Authorities Roll Out New Coronavirus Tests to Gauge Infection’s Spread

Health departments, hospitals and companies around the world are rolling out the next wave in coronavirus tests, which look in a person’s blood for signs of past infection, in hopes of better gauging how widespread the pandemic is and who might be counted among the recovered.

The new tests promise to give public-health and hospital officials a better idea of how widely the new coronavirus has spread and who can safely treat patients and stop social distancing. But uncertainty about the accuracy of some of the tests and unknowns surrounding immunity to COVID-19—the respiratory disease caused by the coronavirus—could limit their usefulness, at least early on.

“To date, we have had no clue how many people have been infected,” said Eran Bendavid, an infectious-disease physician at Stanford University. “This could be an extraordinarily important piece of how we’re going to get over this epidemic.”

In the U.S., the Food and Drug Administration granted the first emergency authorization for one of the blood tests last week, and the Centers for Disease Control and Prevention said it has started using its own test. The U.S. could have a “rather large number of tests” available within a week, provided extra checks show them to be accurate, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN.

China, Germany and Finland are among the other countries using the tests to better understand how the disease spreads.