The health code cannot be modified by itself. The health code is automatically formed by our ID card and our mobile phone number. It cannot change information and content at will. But the health code has been updated.
The "health code" is based on real data and can be generated by citizens or people who have returned to work through their own online declaration and background audit. As an individual entering and leaving electronic certificate locally, the QR code can be declared once, which is universal in the whole city.