Under normal circumstances, the health code needs to be updated every three days in the case of green code, and it can only be extended after the health code is listed in turn within the validity period, otherwise it will be changed to yellow code, but the regulations on health code are different in different regions, so it cannot be used in the same region.
Green codes are health codes based on real data. Citizens or people who return to work after rework can declare online by themselves, and generate personal QR codes after background review. As an individual entering and leaving electronic certificate locally, the QR code can be declared once, which is universal in the whole city.