Soaring Covid-19 caseloads are endangering patients who need urgent medical care at some overwhelmed hospitals, according to doctors, nurses and industry executives in states where the virus has filled beds at or near record numbers.

The overwhelmed hospitals don’t always have the staff or capacity to provide immediate treatment for emergencies from Covid-19 to gallbladder removal, the people said.

“If you’re coming in with a heart attack, is there going to be a delay in your care? Of course there is,” said Scott Steiner, chief executive of the Phoebe Putney Health System, which operates four hospitals in Southwest Georgia and hit its own pandemic record for Covid-19 patients in August.

In Northwest Arkansas last month, two patients who needed transfers from the 36-bed Ozarks Community Hospital to larger hospitals with intensive care units died before staff could find openings, said Ozarks officials.

One of the patients, who was in his 50s and on a ventilator with Covid-19, waited two days as hospital staff searched for an opening at a larger hospital, said Ozarks Administrator Scott Taylor. Another hospital finally agreed to admit him if Ozarks would take one of its more stable patients in exchange.

“We were going to swap,” Mr. Taylor said. “Our patient died before that was possible.”

Nationwide, as the highly transmissible Delta variant of the coronavirus continues to spread, the number of hospitalized Covid-19 patients has climbed above 100,000 for the second time in the pandemic, once more crowding emergency rooms, filling intensive care beds and leaving hospitals short staffed.

Medics transported a Covid-19 patient to a hospital in Houston last month.

Photo: John Moore/Getty Images

A busy hallway at Houston Methodist The Woodlands Hospital last month. Covid-19 hospitalizations in Texas are now near a record.

Photo: Brandon Bell/Getty Images

After earlier surges, hospitals said they had drawn lessons from the experiences and prepared to handle future episodes. Yet current delays providing critical care suggest the pandemic continues to outmatch hospitals’ resources.

Data for the latest surge is limited, but some research from before the pandemic and prior Covid-19 surges indicates that patients’ risk of death increases when hospitals are overrun.

The in-hospital death rate for non-Covid-19 patients increased to about 2.6% from roughly 2.1% as Covid-19 hospitalizations climbed last winter, according to an analysis of seven million hospital stays between March 2020 and July 31.

The higher mortality rate would amount to about 50 additional deaths for every 10,000 non-Covid-19 patients, said Ian Barbash, an assistant professor of medicine at the University of Pittsburgh and ICU doctor.

The data analysis, which used records stripped of identifying information, was provided to The Wall Street Journal by the Epic Health Research Network, which analyzes data from the medical-record software company Epic Systems Corp.

A nurse worked in an intensive-care unit at a Phoebe Putney hospital in Georgia.

Photo: Andres Rengifo

One reason for the increase, researchers who reviewed the data said, might be that healthier patients didn’t seek hospital care as Covid-19 cases surged, leaving hospital beds full with sicker patients who are more likely to die.

The Epic data show total non-coronavirus hospitalizations dropped as Covid-19 patients surged but doesn’t account for whether patients were sicker overall. Studies before the pandemic show mixed results for patient fatality rates when hospitals were slammed.

The stresses of handling surging Covid-19 cases could also have delayed care or overtaxed medical workers with little time to monitor all critical patients, according to researchers.

“Therefore, some patients might have died that otherwise would have survived if the hospitals weren’t under so much strain,” Dr. Barbash said. He said more research was needed to sort out the matter.

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After a rough start to the pandemic, hospitals honed strategies to boost staffing during surges and postpone nonessential medical care to ease strains. Doctors also fine-tuned Covid-19 treatment, learning from early experiences treating patients and taking advantage of newly authorized drugs.

Survival rates for Covid-19 patients improved, according to a study published in July by the Annals of Internal Medicine, which looked at those admitted between March and August last year.

Yet the survival gains faded at hospitals flooded by Covid-19 patients during the pandemic’s spring and summer surges last year, the research found. For Covid-19 patients, the risk of death doubled in the hardest-hit hospitals, the study said.

Staff at a Covid-19 ICU at NEA Baptist Memorial Hospital in Jonesboro, Ark., last month.

Photo: Houston Cofield/Bloomberg News

A patient at NEA Baptist Memorial Hospital in Jonesboro. Arkansas recorded a record number of Covid-19 hospitalizations last month.

Photo: Houston Cofield/Bloomberg News

Childress Regional Medical Center in the Texas Panhandle has struggled during Covid-19 surges to quickly transfer the most critical patients who need care the small hospital can’t provide, said Chief Executive Holly Holcomb.

In October, Childress Regional, in Childress, Texas, sought to transfer a father in his 50s who needed emergency gallbladder surgery, Ms. Holcomb said. Nurses and doctors called other hospitals frantically for nine hours but couldn’t find a larger hospital with an open bed. The patient’s gallbladder ruptured and he died.

Childress Regional is again facing delays after hospitals across Texas grew too crowded to take transfer patients, Ms. Holcomb said. “Our staff just feels helpless,” she said.

The latest surge of Covid-19 hospitalizations has set records in 12 states since the beginning of August and is near a record in Texas.

Patients transferred to hospitals in Georgia’s Phoebe Putney Health System now arrive after long delays from hospitals that lacked the specialists or equipment to care for them, said Kim Whitley, a nurse who oversees transfers for the system.

“You get patients that are sicker than they would have been if you could have gotten them in the door immediately,” she said.

In the second case of a patient death during transfer holdups last month, Ozarks Community Hospital was forced to hold for days a Covid-19 patient in his 40s who needed help breathing, Mr. Taylor said. While waiting for a transfer, the patient suddenly worsened and died, Mr. Taylor said.

Normally, Ozarks Community Hospital would have been able to transfer the patient within a day, Mr. Taylor said. Now the hospital is rushing to assemble the staff and equipment to create a makeshift ICU to care for patients it can’t transfer, he said.

Write to Melanie Evans at Melanie.Evans@wsj.com