The yellow code range of Xihu District of Nanchang City is 250 meters around the high-risk site. According to the relevant public information, the yellow code system refers to the person who stays in a closed or poorly ventilated place or a high-risk place for more than 1 hour at the same time with the case, and the yellow code will be displayed. The yellow code personnel need to complete the nucleic acid detection within 24 hours.