More and more hospitals and major health systems are requiring employees to get the COVID-19 vaccine, citing rising caseloads fueled by the delta variant and stubbornly low vaccination rates in their communities and even within their workforce.

Many hospitals say their efforts to immunize their employees have stalled, in much the same way the nation's overall vaccination rates are stuck under 60%, behind many European countries and Canada. While more than 96% of doctors say they are fully vaccinated, according to the American Medical Association, health care workers, particularly in rural areas, have proved more resistant even though thousands of workers have died from the virus and countless more became sick.

One recent estimate indicated that 1 in 4 hospital workers were not vaccinated by the end of May, with some facilities reporting that fewer than half of their employees had gotten the shots.

Some hospitals, ranging from academic medical centers like NewYork-Presbyterian and Yale New Haven to large chains like Trinity Health, are going ahead with a mandate because they recognize that the only way to stop the virus is to vaccinate as many people as possible, as quickly as possible. A large Arizona-based chain, Banner Health, announced Tuesday that it would impose a mandate, and New York City said it would require all health care workers at city-run hospitals or clinics to be vaccinated or undergo weekly testing.

Watching cases rise prompted Trinity Health, a Catholic system with hospitals in 22 states, to become one of the first major groups to decide earlier this month that it would mandate inoculations. "We were convinced that the vaccine can save lives," said Dr. Daniel Roth, Trinity's chief clinical officer. "These are preventable deaths."

At UF Health Jacksonville, in Florida, the number of COVID patients being treated has surged to levels not seen since January, and only half of its health care workers are vaccinated, said Chad Neilsen, director of infection prevention. Seventy-five employees are out sick with the virus, the vast majority of whom are unvaccinated, while more are waiting for test results. "We are absolutely struggling for staffing right now," he said.

"It's like déjà vu," said Neilsen, who described growing frustration with colleagues refusing to get the shots. "We have a reason to believe this could be over if people got vaccinated."

Despite dozens of virtual town halls, question-and-answer sessions and educational videos, many employees are wary. "We still stagnated," Neilsen said.

Some employees want more data, while others say the process has been too rushed. Many of the same conspiracy theories and misinformation — that the vaccines will make women infertile or contain microchips — hold sway among staff members. "Our health care workers are a reflection of the general population," he said.

Hospital leaders and others plan to meet with state officials in the coming weeks about the possibility of imposing a mandate, he said.

Unvaccinated workers also continue to care for even the sickest patients, raising concerns that they will spread the infection, especially now that the highly contagious delta variant comprises more than 80% of the nation's cases.

"Nowhere is this more important than in hospitals, where health care personnel — who have been heroic during this pandemic — are caring for patients with a wide variety of health challenges under the assumption that the health care professionals treating them are not at risk of acquiring or transmitting COVID-19," Dr. David Skorton, chief executive of the Association of American Medical Colleges, which represents teaching hospitals, said in a statement last Friday calling for a mandate.

Many hospitals already require their employees to get a flu shot, a mandate that has been in place for over a decade. While that was also met by resistance from employees skeptical of the vaccines' safety, it is now largely accepted. Individuals can seek a medical or religious exemption, typically representing a small sliver of the workforce, which hospitals say would also apply to the COVID vaccines.