As states across the American South and West grapple with shortages of vital testing equipment and a key antiviral drug, hospitals are being flooded with coronavirus patients, forcing them to cancel elective surgeries and discharge patients early, and doctors worry that the escalating hospital crunch may last much longer than in earlier-hit areas like New York.

Even as regular wards are being converted into intensive care units and long-term care facilities open for patients still too sick to go home, doctors say they are barely managing.

Hospitals are scrambling to call back nurses and recruit new doctors. Florida Gov. Ron DeSantis announced he was sending 100 nurses to help out Jackson Health System in Miami, which said it had already hired 80 extra nurses in the past two weeks. Jackson Memorial, its flagship hospital, has only 28 I.C.U. beds, out of a total of 234, available.

“When hospitals and health care assistants talk about surge capacity, they’re often talking about a single event,” said John Sinnott, chairman of internal medicine at the University of South Florida and chief epidemiologist at Tampa General Hospital. “But what we’re having now is the equivalent of a bus accident a day, every day, and it just keeps adding.”

Florida is struggling with one of the worst outbreaks in the country, along with Texas, California and Arizona: 43 intensive care units in 21 Florida counties have hit capacity and have no beds available.

In South Carolina, National Guard troops are being called in soon to help insert intravenous lines and check blood pressure. Roper St. Francis Healthcare in Charleston saw a 65 percent increase in coronavirus patients in a single day.

Dr. Christopher McLain, the hospital’s chief physician officer, said he has begun each day on his knees in prayer and often begins meetings the same way, asking the Lord how to respond to the pandemic. “We’re already at a severe condition,” he said.

In Mississippi, five of the state’s largest hospitals have already run out of I.C.U. beds for critical patients, Dr. Thomas Dobbs, the state health officer, said on Thursday. “Mississippi hospitals cannot take care of Mississippi patients,” he said.

Texas Gov. Greg Abbott on Thursday ordered an increase in hospital bed capacity for dozens of counties, extending a ban on elective procedures to new corners of the state in an effort to assist hospitals dealing with the outbreak.

Mr. Abbott directed hospitals to “postpone surgeries and procedures that are not immediately, medically necessary.” The governor had already done so in hard-hit urban counties that include San Antonio, Dallas, Houston and Austin.

At the 463-bed hospital operated by Eisenhower Health in Rancho Mirage, Calif., east of Los Angeles, the coronavirus case count has gone from less than a dozen in May to 77 this week. Most of the 34 intensive care beds are full, nearly half of them occupied by people who have been infected.

“I’m glad some of you are sheltered from what unbridled Covid-19 looks like. It’s a hell show,” a doctor at the hospital, Dr. Richard Loftus, posted to a Facebook physician group after a computer trainer at the hospital turned out to be infected.

Dr. Diego Maselli Caceres at University Hospital in San Antonio, Texas, said he has watched a sevenfold surge of Covid-19 patients needing intensive care over the past month, filling up three floors of the hospital instead of one. His workload has increased to 15 hours a day, he said.

“You get bombarded with multiple calls at the same time,” he said, referring to the “code blue” warnings from overhead speakers that send doctors and nurses rushing to save a patient in distress.

“You hear the calls and you’re running from one end to the other, just like putting out fires, and you’re trying to help as much as you can. It gets overwhelming.”

Hospital bed capacity, including in I.C.U.s, is generally used to gauge a region’s health care infrastructure and the preparedness of its hospitals to respond to the coronavirus. Data showing I.C.U.s at full or near capacity have made headlines recently, but health experts say that attention to capacity does not paint an entirely accurate picture of the severity of the pandemic.

Regular beds are easily converted into I.C.U. capability, doctors and hospital experts say. The bigger challenge is having enough advanced practice nurses who are qualified to care for such patients and equipment such as ventilators.

Hospitals can “pivot enough space,” said Jay Wolfson, professor of public health at the University of South Florida. “The trick is going to be staffing. If you get people burned out, they get sick, then you lose critical care personnel.”

At the Medical University of South Carolina in Charleston, emergency room waiting times can last up to four hours before patients are seen by a physician. The hospital has set up large white tents outside to allow for social distancing, but patients are increasingly leaving the site before their treatment, unwilling to endure the wait.

As physicians and nurses fall ill with the coronavirus, much like their patients, fewer and fewer staff members have been available to accommodate the burgeoning number of sick people at their doorstep. Some emergency room doctors have taken on extra shifts, and the hospital plans to implement a new system where some doctors will be on-call, even on their days off, to respond to the surge.

Mohamed Ibrahim Ali, a critical care doctor at AdventHealth North Pinellas near St. Petersburg, Fla., one of the hospitals that have no more available I.C.U. beds, said that the system was clogged up by patients, sent from nursing homes, who had recovered but had not yet received the all-clear. He said nursing homes have refused to accept residents back unless they have tested negative, a period that could take days.

Roopa Ganga, an infectious disease specialist at two hospitals near Tampa, said that they lacked sufficient supplies of remdesivir, the antiviral drug, forcing her to choose which patients needed it the most. Patients were also being discharged “aggressively” — perhaps too early, she said. They sometimes return a few days later, she said, their symptoms worsened.

“About five people came back in one week last week,” she said. “That is making me feel like, you know, you got to slow down.”

Dr. Wolfson, from the University of South Florida, said health authorities and public officials needed to collaborate better to bypass regulations that bar out-of-state nurses from working in Florida. New York’s Covid-19 crisis in the spring was aided by a number of health workers from outside the state.

“It’s political inertia,” he said. “It takes somebody in a position of significant political stature to say, ‘Let’s do this.’ Florida has always been afraid that people were going to come into the state and take their jobs. Now we need all the help we can get.”

Traveling nurses were brought in to the Eisenhower Health hospital in California’s Riverside County. It was necessary, said Dr. Alan Williamson, the chief medical officer, because the 3-to-1 nurse-to-patient ratio is much higher even for Covid-19 patients who are not in the intensive care beds. It has been a challenge, said Dr. Williamson, because Eisenhower is competing with two other hospitals in the area that are using the same nurse registries to find help.

Texas is experiencing one of the fastest-growing coronavirus caseloads in the country, with new cases exceeding 10,000 one day this week. At the Texas Medical Center hospitals in Houston, the average daily rate of new Covid-19 hospitalizations was 360, nearly double the rate of just two weeks ago.

“The hospitals are full,” said Dr. Esmaeil Porsa, president and chief executive officer of the county’s two-hospital public health system, Harris Health. “We have been over capacity for a couple of weeks.”

In Corpus Christi, Texas, one of the state’s fastest-spreading outbreaks has pushed hospitals to convert floors to treat Covid-19 patients as they scramble to find extra staff, especially nurses.

“Are we strained? You bet we are,” said Barbara Canales, the top official in the surrounding county, adding that hospitals were asking the state of Texas for help on staffing.

The county, of 360,000 people, saw hospitalizations surge in the last few weeks, to 300 on Wednesday, up from fewer than 20 in the middle of June.

Doctors and nurses interviewed said the current spike is unlike anything they have ever dealt with.

Rick Stern, a veteran oncology nurse who works with the Covid-19 patients at Eisenhower Health, said the job is a constant churn of gloves, gowns, masks, face shields and heart-wrenching misery.

His first day in the unit, he said, he watched a cancer patient who had become infected die in the space of 15 hours. At times during this surge, he said, as many as three patients a day have died on his ward; he personally has lost three so far.

One of his current patients is 35.

“I’ve had experience with death,” he said, “but this is different. These people aren’t ready to go yet.”