The yellow code indicates the risk or hidden danger of epidemic infection. Yellow code is the abbreviation of yellow code in epidemic prevention work in COVID-19. Under normal circumstances, residents' health codes will not turn yellow for no reason. When the health code of residents turns yellow, it indicates that there is a risk or hidden danger of epidemic infection. For yellow code personnel, travel is restricted, and they cannot leave hotels, shopping malls, supermarkets, stations, airports, cinemas, KTV, bars and other public places, as well as schools, various prisons, nursing homes, welfare homes and other special places, and adhere to the principle of not going out unless necessary. In daily life, there are many reasons why the health code turns yellow, mainly: 1, staying near the key places where confirmed cases and asymptomatic infected people have stayed, and may have had contact with confirmed cases and asymptomatic infected people. 2, abnormal health, such as fever, shortness of breath, respiratory symptoms. 3. Returnees from other places need to be isolated at home 14 days. 4. Other personnel who need to be included in the "yellow code" management. 5. People from high-risk areas. Key populations for epidemic prevention and control (confirmed cases or asymptomatic infected persons, suspected cases, close contacts and sub-close contacts, people from other provinces with red and yellow health codes, people in centralized isolation, people in family isolation [including people entering our province and other provinces] who have been in centralized isolation or family isolation for more than 14 days but less than 2 1 day, and key populations without nucleic acid detection in the prevention and control area, etc.). ) is managed by the national comprehensive government service platform, the national comprehensive government service platform and the national comprehensive government service platform.