All kinds of health codes are basically docked "communication big data travel cards", which are not restricted by regions and do not collect ID numbers and home addresses. As long as you enter the mobile phone number, you can get the travel information of the past 14 days according to the communication network data. The principle is that the location of the user's mobile phone can be effectively located based on the mobile phone signaling data, so as to find the owner himself.
Health code yellow code personnel should implement measures such as nucleic acid detection and health monitoring, and do personal protection, minimize the flow, and consciously suspend collective activities such as dinner and participation. Do not enter hotels, shopping malls, supermarkets, stations, airports, cinemas, KTV, bars and other public places, as well as schools, various prisons, nursing homes and welfare homes and other special places. If you feel unwell, you should do personal protection, avoid taking public transportation, immediately go to the nearest fever clinic for nucleic acid screening, and report the epidemiological history on your own initiative.