New coronavirus test is imperfect step toward mass screening

WASHINGTON (AP) — A new type of coronavirus test offers a cheaper, quicker way to screen for infections, moving the U.S. toward the kind of mass screening that experts say is essential to returning millions of Americans to school and work.

But the first so-called antigen test — announced Saturday by the Food and Drug Administration — is not quite the kind sought by top government health officials. It is less accurate than the current gold standard for testing and can only be run on specialized equipment.

“It is too early to tell,” said lab researcher Patricia Simner of Johns Hopkins University, assessing the test's impact. “It certainly has the potential to aid in more widespread testing.”

Some questions and answers about the new test:

WHAT'S DIFFERENT ABOUT THIS TEST?

The test from Quidel Corp. screens for new infections but in a different way. It looks for protein traces of the virus — known as antigens. The same approach is used in rapid tests for flu, strep throat and other infections that are run at the hospital or doctor's office. They represent a trade-off, sacrificing some of the accuracy of more rigorous tests for quicker results at a lower cost.

"They allow you to dramatically expand testing and they’re very cheap," said Dr. Scott Gottlieb, the former FDA commissioner, in an interview Sunday with CBS. But he acknowledged antigen testing's reduced accuracy: “They're going to miss some patients who have COVID.”

Previously, the only way to diagnose active infections was a test that detects the genetic material of the virus. While highly accurate, most of those tests take hours to develop on machines mainly found at commercial labs, hospitals or universities. Abbott Laboratories makes a 15-minute version of the genetic test that runs on...