NEW YORK (NYTIMES) - Some of the US' largest employers, for months reluctant to wade into the fraught issue of whether Covid-19 vaccinations should be mandatory for workers, have in recent days been compelled to act as infections have surged again.

On Tuesday (Aug 3), Tyson Foods told its 120,000 workers in offices, slaughterhouses and poultry plants across the country that they would need to be vaccinated by Nov 1 as a "condition of employment." And Microsoft, which employs roughly 100,000 people in the US, said it would require proof of vaccination for all employees, vendors and guests to gain access to its offices.

Last week, Google said it would require employees who returned to the company's offices to be vaccinated, while Disney announced a mandate for all salaried and nonunion hourly workers who work on-site.

Other companies, including Walmart, the largest private employer in the US, and ride-sharing services Lyft and Uber, have taken a less forceful approach, mandating vaccines for white-collar workers but not for millions of front-line workers. Those moves essentially set up a divide between the employees who work in offices and employees who deal directly with the public and who, collectively, have been more reluctant to get the shots.

"We did not take this decision lightly," Tyson's CEO, Donnie King, wrote in a memo to employees announcing the company's full mandate. "We have spent months encouraging our team members to get vaccinated - today, under half of our team members are." The moves brought praise from the White House.

"I want to thank Walmart, Google, Netflix, Disney, Tyson Foods for their recent actions requiring vaccination for employees," President Joe Biden said in a press briefing Tuesday. "Look, I know this isn't easy - but I will have their backs."

"Others have declined to step up," he said. "I find it disappointing."

But most other big employers have avoided mandates entirely. Amazon, the second-largest private employer in the country, has not announced any plans to require immunizations, nor has Apple or many of the biggest banks.

"We are strongly working to get our employees vaccinated," Amazon's chief financial officer, Brian Olsavsky, said in a call with reporters last week, "and we hope everyone else gets vaccinated and this goes away."

The coronavirus, however, shows no signs of going away. With vaccination rates stagnating in many parts of the country and the Delta variant surging, a new wave of infections is forcing businesses to act.

Douglas Brayley, an employment lawyer at Ropes & Gray, said "the rise of the Delta variant is on people's minds." "I think they are looking around and seeing a greater number of employers start to mandate, and so they're wondering whether they should reconsider as well," he said.

But vaccine hesitancy remains an entrenched and emotionally charged issue inside many American workplaces.

Many companies, already facing staffing shortages, are worried that requiring vaccines could give employees another reason to quit. At the same time, companies are struggling for new ways to encourage workers to get vaccinated after efforts like offering cash bonuses did not boost immunization rates quickly enough.

Much of the remaining hesitancy to vaccines appears to be rooted in a complex mix of politics, cultural beliefs and misinformation that no cash payment or gift certificate from an employer can overcome.

"The reason many workers are refusing the vaccine has been for political and ideological reasons," said Stuart Appelbaum, the president of the Retail, Wholesale and Department Store Union, which represents workers in food manufacturing plants in the Midwest, where vaccination rates are relatively low. "In places where we have the largest number of Trump supporters is where we are seeing a large number of vaccine resisters." But many unions are wary of mandates for a different set of reasons. They say many of their members are worried about potential health side effects or bristle at the idea of an employer interfering in what they regard as a personal health decision.

Marc Perrone, the president of the United Food and Commercial Workers union, representing 1.3 million employees in grocery chains like Kroger and at large meatpacking plants, said he would not support employer mandates until the Food and Drug Administration gave full approval to the vaccine, which is being administered on an emergency basis. "You can't just say, 'Accept the mandate or hit the door,' " Perrone said Monday.

After Tyson announced its vaccine mandate Tuesday, Perrone issued a statement that the union "will be meeting with Tyson in the coming weeks to discuss this vaccine mandate and to ensure that the rights of these workers are protected and this policy is fairly implemented." Asked whether he supported vaccine mandates, Appelbaum said, "I am not prepared to answer that yet."

But he did say that companies needed to closely negotiate the terms of any such requirements with workers and that they also needed to expand benefits, such as paid sick time, for workers during the pandemic.

Together, Perrone's and Appelbaum's unions represent more than 30,000 workers in Tyson plants, which complicates the meat company's plans for a mandate.

Tyson and others in the meatpacking industry were criticized during the pandemic's early stages for not doing enough to protect workers as several meat plants became virus hot spots. Now, it is requiring its leadership team to be vaccinated by Sept 24 and the rest of its office workers by Oct 1. Front-line employees have until Nov 1 to be fully inoculated, extra time the company is providing because there are "significantly more front-line team members than office workers who still need to be vaccinated," a Tyson spokesperson said.

Throughout the pandemic, companies have treaded carefully in implementing public health measures while trying to avoid harm to their businesses.

Last year, when major retailers began requiring customers to wear masks, they quietly told their employees not to enforce the rule if a customer was adamant about not wearing one. Companies like Walmart have tried a similarly tentative approach with vaccine requirements.

Walmart announced last week that it was requiring the roughly 17,000 workers in its Arkansas headquarters to be vaccinated but not those in stores and distribution centers, who make up the bulk of its 1.6 million U.S. employees.

In a statement, the retailer said that the limited mandate would send a message to all workers that they should get vaccinated.

"We're asking our leaders, which already have a higher vaccination rate, to make their example clear," the company said. "We're hoping that will influence even more of our front-line associates to become vaccinated."

Uber and Lyft last week both told their corporate employees they would need to show proof they had been inoculated before returning to company offices.

Requiring vaccinations "is the most effective way to create a safe environment and give our team members peace of mind as we return to the office," said Ashley Adams, a spokesperson for Lyft.

But those mandates did not extend to the workers the companies contract with to drive millions of customers to and from their destinations. The drivers are being encouraged to be vaccinated, but neither Lyft nor Uber has plans to require them.

Public health experts warn that limited mandates may serve to reinforce the gaping divide between the nation's high- and low-wage workers without furthering the public health goal of substantially increasing vaccination rates.

They also say it's naive to think that workers who resisted vaccines for ideological reasons would suddenly change their mind after seeing a company's higher paid executives receive the shots.

"Ultimately we want to ensure that they really have the broadest reach," Dr. Kirsten Bibbins-Domingo, the vice dean for population health and health equity at the University of California, San Francisco, said of company directives. "Failing to do that, I think, will only cause others to be more suspicious of these types of mandates." Legally, companies are likely on solid ground if they mandate vaccines. Last year, the Equal Employment Opportunity Commission said employers could require immunization, though companies that do could still face lawsuits.

George W. Ingham, a partner at the law firm Hogan Lovells, said companies with mandates would potentially have to make difficult decisions.

"They are going to have to fire high performers and low performers who refuse vaccines," he said. "They have to be consistent." Reasons an employee could be exempted include religious beliefs or a disability, though the process of sorting those out on an individual basis promises to be an arduous one.

Companies may also have to contend with pushback from state governments. Ten states have passed legislation limiting the ability to require vaccines for students, employees or the public, according to the National Conference of State Legislatures.