How is the epidemic-related area defined in SF Express applet?

How to define the epidemic-related areas in SF Express applet: areas with confirmed cases or asymptomatic infected people within the jurisdiction are judged as epidemic-related areas. Epidemic-related areas refer to areas where viruses or germs can spread, and their scope is limited by the mode of transmission and environmental conditions. Areas with confirmed cases or asymptomatic infections within the jurisdiction are identified as epidemic areas.