In a Georgia emergency department, where patient numbers have swollen even as flu season is fading, staffers are being asked to wash off and re-wear single-use face shields because they are in such short supply.

One sleepless ER physician who has worked in trauma centers and jails and during bomb threats said the chaos caused by the coronavirus pandemic makes her frightened to go to work. Other health-care professionals are setting up separate bedrooms at home to isolate themselves and protect their families.

“ ‘Where are you sleeping tonight?’ That’s the question going around,” said anesthesiologist Michelle Au. Emory Saint Joseph’s Hospital in Atlanta, where she works, has streamlined procedures to accommodate the influx of sick patients, Au said. But the demands on front-line facilities are “beyond the scope of any one medical system to deal with.”

As anxious and infectious patients flock to hospitals across the country, the new virus is exacerbating long-standing pressure points in the nation’s emergency rooms, forcing hospitals to explore ways to reduce exposure even as they provide care.

Temporary triage tents on ambulance ramps, drive- or walk-through screening facilities and greater emphasis on telemedicine are all aimed at relieving the burden on facilities that have a legal — and, many doctors say, ethical — obligation to screen and stabilize everyone who shows up, whether with a broken finger, major trauma, a chronic illness or now, potentially, covid-19.

“We’re trying to keep people out of the ER,” said Frances Lloyd, a nurse practitioner who volunteered to help staff a bright yellow testing tent erected last week in the employee parking lot at the Newton-Wellesley Hospital in Newton, Mass.

The number of people approved to receive testing is growing rapidly, from 46 on Monday to around 100 by midweek, Lloyd said. And the pop-up facility is key, allowing the ER to focus on routine community needs while adapting to new demands imposed by the pandemic.

“Things are changing so fast,” said Jodi Larson, the hospital’s chief quality officer. “We had to figure out how to scale.”

Scaling is not easy in a system that typically operates at maximum capacity, driven in large part by insurance companies’ push to keep costs down.

“Efficiency makes it really hard for ‘just in case,’ ” said Brendan Carr, chair of emergency medicine for the Mount Sinai Health System in New York.

Even major hospitals such as Johns Hopkins in Baltimore have only two or three isolation rooms in their emergency departments. Many big-city hospitals have just one, posing dilemmas: where to house patients who may have covid-19 until they can be moved for treatment — and what happens when the next presumed positive comes in?

“The ED is the gateway to the hospital,” said Lauren Sauer, director of operations at the Johns Hopkins Office of Critical Event Preparedness and Response, and a sign of how well the entire institution is functioning.

Johns Hopkins has set up a large white tent on its ambulance ramp and plans to open a screening center in conjunction with the University of Maryland, much like the new facilities that sprang up in Seattle and Denver. Other cities, including New York, are looking into walk-through facilities that would similarly limit contact among patients and with hospital staff.

“This is 21st-century forward triage,” said Carr, whose hospital is prioritizing telehealth. Many ER patients with respiratory infections are return visitors, Carr said. Once practitioners get a better understanding of where patients are on the risk spectrum, they can offer reassurance or, if necessary, send an ambulance or a paramedic, or encourage them to go to a testing center.

“It’s not just added volume,” said William Jaquis, president of the American College of Emergency Physicians. “It’s seeing additional people who could be highly contagious.”

Add to that what Christopher Greene, a professor of global health and international emergency medicine at the University of Alabama at Birmingham, calls the “pandemic of fear.” It’s natural, Greene said, for people cut off from their usual social support network to say: “I feel ill. I need to go to the ER right away.” “But that’s a very dangerous thing to do,” he said.

Using experience from the H1N1 swine flu epidemic in 2009, clinicians can assess patients’ symptoms and their risk of developing severe illness before they enter the ER. And keeping low-risk or mildly sick patients out is not only in their best interest but in the best interests of other patients.

“There’s a high likelihood they could get infected or infect people who are not infected,” said Paul Kivela, former president of the American College of Emergency Physicians.

The coronavirus crisis comes as many emergency departments throughout the country already struggle to keep up with the volume and variety of problems their patients present. The challenges are compounded by gaps in primary care coverage, particularly for the uninsured.

For many low-income people, emergency rooms are the first stop in the search for health care. Increasing numbers of older patients tend to visit the ER in need of highly complex treatment. And in rural areas, some 60 million Americans rely on hospitals exclusively for their care, although, over the past decade, 119 rural hospitals have closed, according to the Cecil G. Sheps Center for Health Services Research.

“Essentially, we are increasingly the provider of acute, unscheduled care in a lot of communities,” Jaquis said.

Even in cities such as Boston, which has five of the most sophisticated — or Level 1 — adult trauma centers (in addition to two Level 1 pediatric trauma centers), the volume and complexity of ER care had been increasing before this outbreak, according to Eric Goralnick, medical director of emergency preparedness at the city’s Brigham and Women’s Hospital.

“We’re always challenged by capacity, operating at high volumes,” Goralnick said.

At Jefferson Health in Philadelphia, a command center is coordinating across 14 hospitals and seven urgent-care centers to prepare for what doctors anticipate will be a surge in coronavirus cases.

Patricia Henwood, director of global health, said new drive-through and walk-up testing facilities have been set up in some hospital parking lots to accommodate patients within the system who have been identified by their doctors, often through the telehealth program. The flagship hospital’s ER has been divided to segregate people who may be positive, and all triage is being moved outside — steps that are being taken, said Henwood, before the system is actually stressed.

These measures, as well as social distancing, are to protect not just the most vulnerable but anyone who needs treatment in the ER.

“People are not going to stop having strokes and heart attacks and car accidents,” Henwood said.