The desperately ill patients who deluged the emergency room at Detroit Medical Center in March and April exhibited the telltale symptoms of the coronavirus: high fevers and infection-riddled lungs that left them gasping for air.

With few treatment options, doctors turned to a familiar intervention: broad-spectrum antibiotics, the shot-in-the-dark medications often used against bacterial infections that cannot be immediately identified. They knew antibiotics are not effective against viruses, but they were desperate, and they feared the patients could be vulnerable to life-threatening secondary bacterial infections as well.

“During the peak surge, our antibiotic use was off the charts,” said Dr. Teena Chopra, the hospital’s director of epidemiology and antibiotic stewardship, who estimated that more than 80 percent of arriving patients were given antimicrobial drugs. “At one point, we were afraid we would run out.”

Dr. Chopra and other doctors across the country who liberally dispensed antibiotics in the early weeks of the pandemic said they soon realized their mistake.

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