By Robbie Whelan and Sarah Nassauer

American companies began to rethink their requirements for face masks after federal health regulators relaxed their guidelines this week, and on Friday Walmart Inc. made the first big move to bend to the new view.

The U.S.'s largest private employer said it would no longer require vaccinated workers and shoppers to wear masks in stores and warehouses outside of municipalities that require it. Walmart's new no-mask policy for its 1.6 million U.S. workers goes into effect May 18, the company said, while vaccinated customers could shop maskless immediately.

That made the country's largest retailer by revenue an early mover in response to the Centers for Disease Control and Prevention's new guidance. Executives in sectors ranging from autos to grocers said they were still wrestling with how to respond to the new guidelines, which they note conflicts in many cases with state, local and other protocols specific to certain industries.

Car makers General Motors Co. and Toyota Motor Corp. said they are sticking with existing policies while awaiting guidance from the Occupational Safety and Health Administration, which has jurisdiction over their workplaces and still requires face coverings and social distancing. The agency didn't immediately update its guidance based on the CDC announcement. OSHA representatives didn't immediately respond to requests for comment.

Some national retailers said they were reviewing the CDC's changes. Kroger Co., the nation's biggest supermarket chain, said it would continue requiring masks and encouraging social distancing. The company said it is asking employees for feedback as it reviews safety practices and the latest CDC guidance.

Another grocer, Trader Joe's, said it would drop its mask requirements for vaccinated customers. "We encourage customers to follow the guidance of health officials," the company posted on Twitter. It won't require proof of vaccination for those who forgo masks, a spokesperson said.

The CDC said Thursday that fully vaccinated people don't need to wear a mask or physically distance during outdoor or indoor activities, large or small, in most settings. The agency said it made the revisions based on the latest science indicating that being fully vaccinated cuts the risk of getting infected and spreading the virus to others, in addition to preventing severe disease and death.

The Retail Industry Leaders Association, a trade group, said the CDC's mask announcement creates ambiguity since it doesn't align with state and local orders. The group asked customers who decline to wear masks to shop online or use curbside pickup services.

"Retailers will continue to prioritize the safety of their team members first, as they've done throughout the pandemic," said Lisa LaBruno, a senior vice president at the group. "We urge all retail customers and guests to follow a store's safety protocols including wearing a mask and social distancing."

At Walmart, to go maskless, workers have to say they are vaccinated during the health screenings each worker takes to start a shift, the company said. The retailer continues to review whether masks should be worn for certain jobs, said a companywide email Friday, and workers can continue to wear masks if they want to.

The relaxed mandate could allow bigger crowds to gather. Walt Disney Co. Chief Executive Bob Chapek said he expects to see an immediate increase in the number of people allowed inside domestic theme parks following the CDC move. "Today's guidance," he said Thursday, "is very big news for us, particularly if anyone has been in Florida in the middle of summer with a mask on."

Food makers Conagra Brands Inc., General Mills Inc. and Kellogg Co. said they are continuing to require masks and social distancing at their factories even as employees get vaccinated, as food manufacturers have to follow a range of industry-specific regulations.

The Consumer Brands Association, a trade group for food and other grocery manufacturers, said it has asked the CDC for more details on how its latest mask guidance affects businesses such as factories.

Betsy Booren, senior vice president of regulatory affairs for the group, said that the revised guidance seemed directed mainly at consumers in their daily lives but that food factories, where workers are often crowded together and can't always distance, present different circumstances. Ms. Booren said that while she is encouraged by the latest CDC guidance and what it might mean for returning to normal, she hesitates to advise manufacturers to change their practices.

Restaurants face complicated decisions in part because they have employees and customers who could be unvaccinated, and operators can't easily distinguish who has been inoculated and who hasn't. Many also face state and local regulations that require mask-wearing on their premises.

While restaurants want to return to normal so they can get more business, they also want diners to feel safe enough to return, said the National Restaurant Association, which has decided not to update its masking guidance immediately.

Larry Lynch, senior vice president of science and industry for the association, said he is "encouraged by the CDC's decision and the potential it has to help move the restaurant industry closer to being fully reopened."

Paul Mangiamele, chief executive of Legendary Brands LLC, a Dallas company whose franchisees include roughly 80 Bennigan's pubs and Steak and Ale restaurants in the U.S., said he expects most of his franchisees to remove masking restrictions in the coming days. But the company will let individual restaurants decide how to verify vaccination status. He expects most restaurants to make masking optional for employees and to benefit from a flood of pent-up demand.

"We want to react immediately to the guidance that's provided, but do that with common sense and safety," Mr. Mangiamele said.

In Philadelphia, McGillan's Olde Ale House, a 150-year-old Irish pub near the city's downtown, is operating at 50% capacity and requiring masks and social distancing for all patrons and employees, except while eating and drinking. Owner Chris Mullins is waiting for the city's guidance before lifting the pub's mask requirement. Local health officials have said they hope to remove all capacity and distancing precautions by June 11.

"Everyone's excited, and they want the extra money and the increased business," Mr. Mullins said. "But the potential for every night being New Year's Eve, with five deep at the bar and people screaming in your face for a beer, is still a little jarring to some of my employees, too."

Small businesses aren't certain how to respond to the CDC's new mask guidance, especially when it conflicts with OSHA's and other guidelines, said Kevin Kuhlman, head of government relations for the National Federation of Independent Businesses, a trade group representing 300,000 mostly small, private companies.

Many small businesses hope state and local governments endorse the CDC's view on masks soon. Meanwhile, were OSHA to issue any new emergency guidelines that conflict with the CDC's advice, "that would really confuse small businesses," Mr. Kuhlman said. "Our biggest fear is getting something brand new from OSHA that's even more restrictive."

Dropping mask requirements -- along with widespread vaccine availability and falling case rates -- would help bring more white-collar workers back to offices, said Kenneth Caplan, global co-head of real estate at Blackstone Group Inc. As an owner of office space, he said he has noticed more talk of businesses bringing employees back.

"It's another positive step, but it's part of a continuum of a lot of steps toward reopening," Mr. Caplan said.

--Christina Rogers, Jaewon Kang, Annie Gasparro and Craig Karmin contributed to this article.

Write to Robbie Whelan at robbie.whelan@wsj.com and Sarah Nassauer at sarah.nassauer@wsj.com

(END) Dow Jones Newswires

05-14-21 1801ET