The cause of the epidemic. McDonald's canceled the all-day breakfast menu to simplify its operation, because the epidemic situation made the restaurant's operation more tense. Bill Garrett, senior vice president of McDonald's US operations, said in a statement: "In order to simplify the operation of the kitchen and staff and ensure the best experience for customers, we are working with franchisees and local restaurants to focus on serving our most popular choices and will begin to temporarily delete some items from the menu. In the next few weeks, we will evaluate the situation regularly and hope to return to our regular menu as soon as possible. "