Before the coronavirus pandemic, Ivette Palomeque made $45 an hour on a flexible schedule as a staff intensive-care nurse at Memorial Hermann Health System in Houston.

Today, she earns $120 an hour working in an ICU in McAllen, Texas, the latest in a string of “travel nurse” jobs she has held over the past 16 months. The journey that has taken her from Miami to New York City and back to Texas.

She plans to work high-paid crisis contracts as long as she can. Nursing pay may never be this good again, she said, and persistent understaffing means that working conditions for staff nurses aren’t likely to improve.

“Going back to a staff job is just not an option,” said Ms. Palomeque, 45 years old. “Absolutely not.”

The pandemic has altered the labor market for nurses and other medical staff. As Covid-19 spread in spring 2020 and filled emergency rooms with sick patients, thousands of hospital staffers were drawn by sky-high pay and the chance to help hard-hit communities like New York City. Others left the profession after long months treating critically ill patients.

Fueled by intense demand, and paid for in part with federal emergency funding to hospitals, travel-nurse pay has skyrocketed. In December 2019, average gross weekly wages for a travel nurse were around $1,600 a week, according to data from Vivian Health, a healthcare recruiting company. One year later, average pay was more than $3,500 a week.

After declining from a winter peak, pay is rising again as the Delta variant rages through states with lower vaccination rates. Average weekly gross wages for a registered nurse working on a travel contract in the U.S. rose to $2,597 in early August, the highest rates since February, Vivian Health said.

High crisis pay is exacerbating a chronic shortage of permanent medical staff across the country, which predates the pandemic and extends to all parts of the healthcare system. Hospital leaders expect their labor crunch to persist long after the pandemic has calmed.

At Harris Health System in Houston, vacancy across 2,200 bedside nursing positions is about 22%, up from 8% before the pandemic. Harris Health said in mid-August that it would raise pay for all emergency-department and adult-ICU nurses to $140 an hour until staffing levels stabilize.

Ivette Palomeque at her apartment in Texas. She is living with her sister, who is also a travel nurse.

“The hospital is not going to be able to survive on hiring travel nurses in perpetuity,” said Maureen Padilla, Harris Health’s senior vice president for nursing services.

Shortages have created a skills gap at Harris Health, Ms. Padilla said: Inexperienced nurses are helping with more complex care, leading to higher risk of mistakes.

“These days, where I lose sleep every night is, how are we going to stop this vicious cycle?” she said.

Hospitals have reported chronic nurse shortages for several years. The National Institutes of Health estimates that there was a shortage of about one million nurses in the U.S. in 2020.

The added pressure from the pandemic and high pay rates for travel nurses could spur a permanent reset of wages for all nurses, said April Kapu, president of the American Association of Nurse Practitioners.

“This pandemic has highlighted how important nurses are to the workforce, so bringing their pay in alignment with the market is more important than ever, because nurses are going to expect that,” Ms. Kapu said.

Rachel Norton, a registered nurse from Albany, took a temporary travel assignment in Denver in mid-2019. When the pandemic hit, the hospital in Denver offered her a $1,000 weekly bonus to extend the assignment, and she accepted. Since then she has taken crisis assignments in Arizona and California as well, and doesn’t plan to return to the East Coast.

Ivette Palomeque and her twin sister, both travel nurses, after working the night shift at a hospital in McAllen, Texas.

“Once nurses are done with a crisis contract, they don’t want to go back to the bedside where they know they’re going to be short-staffed and underpaid,” Ms. Norton said.

Some hospitals are offering once unheard-of signing bonuses for nurses who accept longer assignments: $40,000 at Monument Health’s hospital in Rapid City, S.D., $20,000 at Temple University Hospital in Philadelphia, and $10,000 at St. Charles Health in Bend, Ore., according to the hospitals.

Allegheny Health Network in Pittsburgh is offering $15,000 bonuses to nurses who sign long-term contracts. Chief Nurse Executive Claire Zangerle said the system and many other hospitals can’t match the pay and benefits, such as vacation time, that some staffing agencies offer.

“Most of us are not-for-profit, and these labor costs are not in our budgets,” she said. “We’re desperate for nurses.”

FROM THE ARCHIVES

Traveling nurses are offsetting staffing shortages in hospitals around the U.S. where Covid-19 is surging. Four nurses give viewers an intimate look into the mental and physical toll the work is having on them five months into the pandemic. Photo: Chelsea Walsh The Wall Street Journal Interactive Edition

Catrina Rugar, an ICU nurse who lives with her husband and six children in Homosassa, Fla., has left her house every Wednesday at 2:45 a.m. since February for her 7 a.m. crisis shift at a hospital in Fort Myers. She works 12-hour shifts for three days straight, then drives three hours home again to spend the rest of the week with her family.

Over the past year she has worked in ICUs and at testing sites in New York, Texas and Florida. Each job has paid more than $100 per hour, compared with the $34 she made at a hospital near her home before the pandemic. When her Fort Myers contract ends in a few weeks, she’s lined up another crisis-pay gig in the Miami area.

“It’s a no-brainer if you’re making double or triple money,” Ms. Rugar said.

Phoebe Putney Health System, which operates four hospitals in Southwest Georgia, added two ICUs in recent weeks, and hit a record for Covid-19 hospitalizations on Aug. 19. For every additional intensive-care bed, Phoebe Putney needs about four more nurses, said Scott Steiner, the system’s chief executive officer.

“It adds up real quick,” he said.

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Phoebe Putney tries to extend contracts of its travel-agency nurses; that can mean offering a higher wage to persuade them to stay, Mr. Steiner said. The system is training employees without clinical skills to do jobs that don’t require medical knowledge, from bathing patients to emptying urine bags, he said.

“We’re living for the moment right now,” he said in mid-August. “That’s not a good place to be.”

—Melanie Evans contributed to this article.

Write to Robbie Whelan at robbie.whelan@wsj.com