New York City’s soundtrack has always included the sound of ambulance sirens. But now, with many of the city’s businesses closed and its neighborhoods quiet, endless wailing seems to echo through the deserted streets.

Three weeks ago, the paramedics said, most coronavirus calls were for respiratory distress or fever. Now the same types of patients, after having been sent home from the hospital, are experiencing organ failure and cardiac arrest.

“We’re getting them at the point where they’re starting to decompensate,” said the Brooklyn paramedic, who is employed by the Fire Department. “The way that it wreaks havoc in the body is almost flying in the face of everything that we know.”

In the same way that the city’s hospitals are clawing for manpower and resources, the virus has flipped traditional Emergency Medical Services procedures at a dizzying speed. Paramedics who once transported people with even the most mild medical maladies to hospitals are now encouraging anyone who is not critically ill to stay home. When older adults call with a medical issue, paramedics fear taking them to the emergency room, where they could be exposed to the virus.

One paramedic told a 65-year-old patient in Brooklyn, whom she had previously transported to the hospital for recurring issues, to stay home this time and call a doctor.

In New York City, 911 calls are handled by both Fire Department ambulances and ambulance companies staffed by area hospitals. Their duties are effectively the same: They respond to the same medical calls, largely determined by what crew is closer and which is available fastest.

Neither the city, the State Department of Health or the federal Centers for Disease Control and Prevention have issued strict rules as to how paramedics should respond to a coronavirus call. In recent days, Fire Department policy — which applies to all ambulance crews in the 911 system — has given more latitude to paramedics to make decisions on how to handle patients they believe have the virus.