[Aljazeera] 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.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 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.