(Bloomberg) -- Walmart Inc., the largest private employer in the U.S., is requiring its headquarters and regional staff to be vaccinated by Oct. 4, joining Alphabet Inc.’s Google in instituting a policy that other big companies may soon follow as the delta variant continues to spread.

The mandate covers all campus staff, as well as market, regional and divisional employees who work in multiple facilities, Chief Executive Officer Doug McMillon said in a memo Friday. A Walmart spokesman couldn’t immediately say how many people that entails. The policy includes all new hires as well. Walmart separately told its frontline store and warehouse associates Friday to don masks again, and doubled the cash incentive it’s providing for employees to get vaccinated to $150.

“The pandemic is not over, and the delta variant has led to an increase in infection rates across much of the U.S.,” McMillon said in the memo. “We have made the decision to require all campus office associates and all market, regional and divisional associates who work in multiple facilities to be vaccinated by Oct. 4, unless they have an approved exception.”

Walmart’s new policy set a standard that other retailers and big companies may soon follow, as infections from Covid-19 variants surge across the nation. Google will also require workers coming back to its offices be vaccinated, but pushed back its return-to-campus date to Oct. 18. Apple Inc. also delayed its return-to-office to October and began urging store workers to wear masks again.

McMillon said there’s a “small percentage” of employees who can’t get vaccinated due to medical or religious reasons, and the spokesman said they “must follow all social distancing standards, wear a mask while working, and receive weekly Covid-19 testing provided by Walmart.” Employees at Walmart’s Bentonville, Arkansas, headquarters have been gradually coming back to offices with the intention of returning to pre-pandemic staffing levels after Labor Day. Now, though, McMillon said he might need to adjust that timing.

Walmart said it’s also limiting business travel to mission-critical trips, which could dent the resurgence of air travel if its policy is followed by other big companies.

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