NEW YORK (AP) - Walmart is requiring that all workers at its headquarters as well as its managers who travel within the U.S. be vaccinated against COVID-19 by Oct. 4.

The retailer based in Bentonville, Arkansas, is also reversing its mask policy for its employees working in stores, clubs, distribution facilities and warehouses. Going forward, they will be required to wear masks in areas with high infection rates, even if they have been vaccinated.

The moves are part of a series of sweeping measures the nation's largest retailer and private employer announced Friday to help curb the spread of the virus and drive more of its workers to get the shot in the arm.

The vaccine mandate excludes frontline workers, who the company says have a lower vaccination rate than management. But it's hoping that managerial employees, who represent just a fraction of its 1.5 million workers, will serve as inspiration.

“We're hoping that will influence even more of our frontline associates to become vaccinated,” Walmart spokesman Scott Pope said.

Pope declined to break out the vaccination rate for frontline workers and the rest of Walmart's employees.

Walmart is also encouraging customers to wear masks in stores located in areas with surging cases and will be adding back signs at the entrances. It will also bring back so-called health ambassadors who will be stationed at the entrances and hand out masks.

The company is also doubling to $150 the incentive it is offering to workers in stores, clubs, as well as other facilities like distribution centers, to get the vaccine. Those who already received the $75 incentive will receive another $75 in their paycheck dated Aug 19.

The steps come three days after the Centers for Disease Control and Prevention changed course on some masking guidelines, recommending that even vaccinated people return to wearing masks indoors in parts of the U.S. where the delta variant of the coronavirus is fueling infection surges.

Walmart's move to require vaccinations of its workers at its headquarters follows Google's steps announced earlier in the week that it's postponing a return to the office for most workers until mid-October and rolling out a policy that will eventually require everyone to be vaccinated once its sprawling campuses are fully reopened. Google's announcement was shortly followed by Facebook, which also said it will make vaccines mandatory for U.S. employees who work in offices. Exceptions will be made for medical and other reasons.

Various government agencies already have announced demands for all their employees to be vaccinated, but the corporate world so far has been taking a more cautious approach, even though most lawyers believe the mandates are legal.

Delta and United Airlines are requiring new employees to show proof of vaccination. Goldman Sachs and Morgan Stanley are requiring their workers to disclose their vaccination status, but are not requiring staffers to be vaccinated.

However, given Walmart's outsized influence on the economy, more companies could make similar announcements.

In fact, following Walmart's announcement, the Walt Disney Co. said Friday it's requiring all salaried and non-union hourly employees in the U.S. working at any of its sites to be fully vaccinated. It said workers who aren't already vaccinated and are working on site will have 60 days from Friday to complete their protocols. Those who are still working from home will need to provide verification of vaccination before their return. Disney also said that all new hires will be required to be fully vaccinated before starting employment.

“Vaccines are the best tool we all have to help control this global pandemic and protect our employees,” Disney said in a statement. Disney has about 200,000 employees but it is unclear how many of them are affected. The company based in Burbank, California, did not respond to questions

Grocery chain Kroger announced Friday that it will be encouraging all customers, workers and suppliers, including those who received the shot, to wear masks at its stores. But the company said it will not be issuing a vaccine mandate for its employees.

Ken Perkins, president of the retail research firm Retail Metrics, said that Walmart's move could serve as a “green light” to other companies to require vaccines, given its massive following and its location.

“It's based in the middle of the country,” Perkins said. “They speak to the lower-, middle-income shoppers and workers.”

Walmart's dramatically shifting policy reflects the growing worry about the rising infection rates.

“We continue to watch with deep concern the developments of the pandemic and the spread of variants, especially the delta variant,” wrote Donna Morris, Walmart's chief people officer, in the memo circulated to employees that was shared by the company. “We know vaccinations are our solution to drive change. We are urging you to get vaccinated and want to see many more of you vaccinated.”

In a separate memo sent to employees who work at the company headquarters, Doug McMillon, president and CEO of Walmart Inc., wrote, “The virus is not over, and the delta variant has led to an increase in infection rates across much of the U.S.”

The retailer has seen a “positive response” to the first financial incentive and is anticipating the sweetened perk will drive a similar response from workers, Pope said.

He stopped short of saying that office workers who declined to be vaccinated would be terminated but said that Walmart is working through the process. He noted that the exceptions would be those who can't get vaccinated for medical or religious reasons.

When asked why frontline workers won't be required to get the vaccine, Pope said that its approach with its large number of workers in frontline facilities has been “to inform them, encourage them, make it easy and to reward then financially for choosing to receive the vaccine.”

Walmart said it is also implementing a new process for verification of vaccine status for U.S. workers. It says it will share those details in the future.

A few days after the CDC eased mask-wearing guidance for fully vaccinated people back in May, Walmart, along with a slew of other retailers, said it wouldn't require vaccinated shoppers to wear a mask in U.S. stores, unless state or local laws said otherwise. Walmart also said that vaccinated workers could go maskless.

At that time, Walmart said that customers wouldn't be asked but rather held to an “honor system” regarding their vaccination status. Walmart workers who didn't wear masks also had to confirm they were vaccinated by filling out a daily questionnaire, though it was not requiring proof.

AP Technology Writer Michael Liedtke in San Francisco contributed to this report.