Walmart Inc., the largest private employer in the U.S., is requiring its headquarters and regional staff to be vaccinated by Oct. 4, joining Google in instituting a policy that may set a standard for corporate America as the highly contagious delta variant continues to spread. Walt Disney Co. followed with a mandate of its own.

Walmart’s action 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 spokesman couldn’t immediately say how many of the retailer’s 1.5 million-person U.S. workforce will be affected. 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.”