If an employee is diagnosed after returning to work, the first step is to find out who the patient has been in contact with recently and where he has been going. Secondly, it is also important to find out clearly with the employees of the unit who have been in contact with him. These close contacts are implemented for 14 days of intensive isolation and observation, during which time if the close contacts are found to have fever, malaise, dry cough, stuffy nose, runny nose, sore throat, diarrhea and other uncomfortable symptoms, they should immediately seek medical attention. If a confirmed patient is not detected early and widespread transmission occurs in units and enterprises, certain measures should be taken for the enterprise or unit at this time.