If you go to the quarantine area or the confirmed area, the other person may change color, but if you have never been to or contacted the relevant personnel, the health code will not change color.
Health code is a personal two-dimensional code based on actual real data, which is generated by citizens or people who have returned to work on 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.