The United States' number 1 retailer with 4,700 stores in the country, Walmart said that vaccinated customers can shop without masks.

The company also said that fully vaccinated workers can also work without masks from  May 18.

The company also said it is giving $75 bonuses to vaccinated workers as "a thank you for getting vaccinated," but employees will need to provide proof of vaccination to get the money.

"We will continue to request that non-vaccinated customers and members wear face coverings in our stores and clubs. We will update the signage in our facilities to reflect this," the memo to both Walmart and Sam's Club employees said. 

Kroger, the largest U.S. supermarket chain, said the company would still require everyone in its stores to wear masks and continue to encourage social distancing. The company also said it is reviewing the CDC's latest guidance to develop "the next phase of our policy."