• McDonald's, Target and Kohl's will begin requiring masks for store employees in high-risk counties in the United States as determined by the latest CDC rankings.
• The rules for both retailers go into effect Tuesday.
• The shift in policy comes after Walmart on Friday started requiring masks for its store staff in counties with high rates of Covid transmission.

McDonald's, Target and Kohl's are the latest companies to require masks for store employees in areas where people are at a high risk for Covid-19 as determined by the latest CDC rankings.

The rules for both retailers go into effect Tuesday, while the fast-food giant's policy is effective Monday. McDonald's shared the policy change with its franchisees and employees on Friday.

McDonald's is also requiring that customers wear masks inside restaurants located in high-risk areas, regardless of vaccination status. Target and Kohl's said the companies will strongly recommend face coverings for all shoppers in those counties, as well, but will not be enforcing the guideline.

"We'll follow all local mandates, as we have throughout the pandemic, and continue to monitor guidance from the CDC closely," a spokesperson for Target said in a statement.

Separately, Home Depot said that beginning Monday it will again be requiring workers, contractors and vendors to wear masks in all of its stores, warehouses, offices, and customers' homes and businesses — regardless of vaccination status.

The home improvement chain said it will ask all customers to wear masks in its stores, too, and will be offering masks to those who don't have one.

On Friday, Walmart made an early shift in policy to begin requiring masks again for its store staff in counties with high rates of Covid transmission. The changed policy followed a new recommendation from the Centers for Disease Control and Prevention calling for people to wear face masks again in areas where the Covid-19 virus is spreading the most rapidly. It currently covers about two-thirds of all U.S. counties.

In May, the CDC had said that vaccinated individuals could unmask. But the delta variant has led to a resurgence in cases, forcing the agency to reevaluate. The increase in cases is most pronounced in parts of the country where vaccination rates are lower. The CDC has warned that the delta variant is as contagious as chickenpox, has a longer transmission window than the original Covid-19 strain and may make older people sicker.

The back-and-forth is putting retailers in a tough spot. Many businesses have workers on the front line as well as in corporate offices, and companies are being forced to reconsider masking and vaccination policies for both.

Walmart, for example, has told its corporate staff and management-level employees that they must be vaccinated against Covid-19 by Oct. 4. It has not, however, mandated the vaccine for its store and warehouse workers. It has offered bonuses for those workers who do get the shots.

The New York City-based real estate developer Related Companies is also mandating all of its workers to have at least their first vaccine shot by Aug. 31.

"Being vaccinated will be a requirement to work at Related," the company said in a memo sent to workers on Monday morning.

SoulCycle parent Equinox Group is asking its members, riders and staff to show one-time proof of vaccination in order to enter its New York City facilities, beginning early next month. Principals of Related are investors in Equinox.

Target said Monday that it will continue to encourage workers and customers to get inoculated by offering vaccine appointments at all CVS locations within Target, and also by offering paid time off and free Lyft rides for those appointments.

— CNBC's Amelia Lucas contributed to this report.