With some vaccination mandates taking effect, hundreds of Americans who refuse to get inoculated are now out of work – and thousands more could soon join them. 

Companies that have required employees to get vaccinated for COVID-19 are reporting that the vast majority have complied. But there have been holdouts, in some cases enough to fuel concerns about staffing levels.

Earlier this month, President Joe Biden ordered all federal workers and contractors to be vaccinated. He also announced plans for private companies employing at least 100 people to ensure workers are inoculated or pass COVID-19 tests at least weekly, but the Occupational Safety and Health Administration (OSHA) is still crafting that rule. 

The firings happening this week are largely related to mandates issued by private companies and state governments.

A spokesperson for North Carolina-based Novant Health, which serves North and South Carolina, Georgia and Virginia, said Tuesday that about 175 unvaccinated employees across 15 hospitals and 800 clinics have been fired. The company’s compliance rate for its 35,000 workers, however, is over 99%.

“We stand by our decision to make the vaccine mandatory as we have a responsibility to protect our patients, visitors and team members, regardless of where they are in our health system,” Novant Health said in a statement. “We couldn’t be prouder of our team members who made the choice to receive the covid-19 vaccine and remain part of our team at Novant Health.”

ChristianaCare, another health care network which serves Delaware and parts of neighboring Pennsylvania, Maryland and New Jersey, about 150 employees, including some part-timers, were terminated for not getting vaccinated, CEO Janice Nevin said Monday. The noncompliance rate there was about 1%. The company says it already has hired more than 200 new employees. 

The impact of a vaccine mandate, however, is being felt more in New York state, where the requirement for health care workers went into effect Monday at midnight. 

The state’s health department said about 16% of hospital workers and 11% of nursing home staff were unvaccinated, amounting to tens of thousands of health care workers. 

Faced with staffing shortages, Gov. Kathy Hochul is preparing to declare a state of emergency that would allow nurses from other states to help fill vacancies and medical professionals with the National Guard to be deployed.

“The only way we can move past this pandemic is to ensure that everyone eligible is vaccinated, and that includes those who are taking care of our vulnerable family members and loved ones,” Hochul said in a statement.

Northwell Health, which has hospitals in and around New York City, told Newsday on Monday that it has fired about two dozen employees and that the number could grow. Thousands of other health care workers across the state are also facing termination or have been placed on unpaid suspension.

Meanwhile, Untied Airlines said late Tuesday it will begin terminating 593 employees over the next few days for refusing to get vaccinated, but later amended that figure, saying in a statement Thursday that "in less than 48 hours, the number of unvaccinated employees who began the process of being separated from the company has been cut by almost half," falling to 320.

"Our vaccine policy continues to prove requirements work," the company said THursday, noting that now 99.5% of its domestic workforce of 67,000 is vaccinated, "excluding those who sought an exemption."

CNBC reports that about 2,000 United employees sought medical or religious exemptions to the mandate.

"This was an incredibly difficult decision but keeping our team safe has always been our first priority," the company's CEO Scott Kirby and president Brett Hart wrote in a memo to staff.

A spokesperson for the airline told the New York Times that "we will work with folks if during that process they decide to get vaccinated."

And more vaccination deadlines are approaching in other states, including for health care workers in Oregon, Rhode Island and Minnesota, and for state workers in Washington state.

Dozens of other large companies, including Amtrak, Microsoft, Disney, Google and Goldman Sachs, have, too, issued ultimatums to most workers. And smaller companies in New York, San Francisco and New Orleans have been required to implement mandates for customers and workers.

Like many Americans, some workers are reluctant or skeptical of the vaccines. Despite that numerous studies have found the shots to be safe and effective, some have concerns about potential side effects. 

“For me, there is just a lot of unknowns about the risks, what could potentially happen,” Laura Rushing, a nurse with Novant Health, told Spectrum News last week. “Sure, you can take it and nothing happens, but what if I’m the one who takes it, heaven forbid, I die or I’m incapacitated? I’m a single mom.”

Others have asked for exemptions for health or religious reasons, but not all are granted. And some health care workers have said they are simply opposed to the idea of an employer forcing them to be vaccinated.

“This is not the same as having all the other vaccines that we've been around for years,” said Nanette Petersen, another Novant employee. “It's not the same. This is a new one, so I want to see what happens.”

Some employees are fighting the mandates in court. For example, more than 180 health care workers in Minnesota are asking for an injunction to stop their hospitals from imposing the requirement, arguing it violates religious freedom and other state and federal laws. 

In New York, a judge granted a temporary restraining order to the state’s vaccinate mandate for health care workers who claim religious exemptions until Oct. 12, when he revisits the case. 

Also, a group of federal workers and contractors sued the U.S. government last week over Biden’s mandate. And United is facing a pair of similar lawsuits.

But the mandates do appear to be making a dent in the nation’s vaccination rate. 

“The experience says these mandates do move the needle quite a bit on employees’ willingness to get vaccinated,” said Laura Boudreau, an assistant professor at Columbia University who studies labor issues. She said she believes that only a tiny fraction of employees will quit — likely those already close to retirement and who strongly distrust vaccines.

United officials say about 96% of the airline’s 67,000 U.S. employees have been vaccinated and another 3% are seeking an exemption, which could result in being placed on unpaid leave. Fewer than 1% will be fired, which officials said would not affect airline operations.

In Washington state, where 63,000 state workers will be required to be inoculated by Oct. 18, the vaccination rate among them jumped from 49% on Sept. 6 to 68% just two weeks later.

In August, San Francisco became the first major city in the nation to require proof of full vaccination against COVID-19 for people dining inside restaurants, with employees having until Oct. 13 to get the shot. Akash Kapoor, founder of the Curry Up Now Indian restaurant chain, said more than 90% of his employees in his downtown San Francisco location are now vaccinated, with one or two per store refusing. He’s making unvaccinated workers get tested twice a week.

Alejandra Segura, 28, a senior learning and development coordinator at Curry Up Now, said she was worried about having a bad reaction to the vaccine, so she held off. But the vaccination mandate spurred her into action, and she received her first dose of the Pfizer vaccine on Sept. 20.

“It's a good thing we're required to get the vaccine, to ensure people's safety,” Segura said.

As of Tuesday, 185.3 million Americans, or 55.8% of the population, has been fully vaccinated. Two-thirds of adults are fully inoculated.

NOTE: This article has been updated to reflect an adjusted total to United's vaccinated workforce.

The Associated Press contributed to this report.