There are three health codes: green, yellow and red. Among them, the green code means "no abnormality" and can pass normally; The yellow code will restrict travel and require "home isolation"; Red team needs quarantine 14 days. If the health code changes to red team, it means contact with the confirmed case. At this time, it is necessary to report to the local community immediately, and then it is necessary to concentrate on isolation 14 days, during which nucleic acid testing should be carried out regularly and self-health monitoring should be carried out. Only when the isolation period expires and the nucleic acid test result is negative can the isolation be lifted.