The directive, issued by the U.S. Food and Drug Administration, requires that the Centers for Disease Control and Prevention, a sister agency, retest every positive coronavirus test run by a public health lab to confirm its accuracy. The result, experts say, is wasting limited resources at a time when thousands of Americans are waiting in line to get tested for COVID-19.

The duplicative effort is the latest obstacle that is slowing the federal response to COVID-19, which has infected more than 1,300 people and resulted in 38 deaths in the United States. Progress was already delayed because the CDC decided to make its own test rather than adopting the design endorsed by the World Health Organization. The test then didn’t work properly and had to be fixed. The problems were further compounded by delays in certifying tests by private laboratories as well as a shortage of supplies and raw materials used for testing…

“This is the time when we need as many tests as we can very quickly, because we need to know what is happening in this country,” said Dr. Leana Wen, an emergency physician and former health commissioner for the city of Baltimore. “Right now we are in the dark about the degree of COVID-19 spread. It’s hard for us to proceed to do our work in public health without concrete information.”