Scientists on Wednesday announced the first effective treatment against the coronavirus — an experimental drug that can speed the recovery of COVID-19 patients — in a major medical advance that came as the economic gloom caused by the scourge deepened in the U.S. and Europe.

The U.S. government said it is working to make the antiviral medication remdesivir available to patients as quickly as possible.

"What it has proven is that a drug can block this virus," said Dr. Anthony Fauci, the government's top infectious-disease expert. "This will be the standard of care."

Stocks surged around the wor...