Liao Shitong health code is a dynamic code. If the applicant has ever taken a bus with a confirmed or suspected case, or comes from a key epidemic area, it will affect the color of the health code.
There are many sources of health code data collection, and everyone's mobile phone operation can basically be recorded. For example, the QR code of mobile payment, public transportation such as bus and subway, the GPS location information of users recorded by WeChat and Alipay in the background, and even the location information of base stations connected to mobile phones can all be used as data sources of health codes.