After going to high-risk or medium-risk areas, the health code system will automatically change to "red team" or "yellow code" in 14.
People who have time and space to follow up the confirmed cases or asymptomatic infected people in COVID-19 will be given a "yellow code". Space-time companionship refers to the mobile phone number that collides with the track for a specified time (such as 10 minutes or more) in an outdoor open space within a certain distance from the same base station, and is defined as "space-time companionship" that may be exposed.