Problem

Last week, just as the Food and Drug Administration was preparing to issue an emergency authorization for blood plasma as a Covid-19 treatment, a group of top federal health officials including Dr. Anthony S. Fauci intervened, arguing that emerging data on the treatment was too weak, according to two senior administration officials.

The authorization is on hold for now as more data is reviewed, according to H. Clifford Lane, the clinical director at the National Institute of Allergy and Infectious Diseases. An emergency approval could still be issued in the near future, he said.

For months, public health experts and federal officials have said that significantly expanding the number of coronavirus tests administered in the United States is essential to reining in the pandemic. By some estimates, several million people might need to be tested each day, including many people who don’t feel sick.

But the country remains far short of that benchmark and, for the first time, the number of known tests conducted each day has fallen.