1. division standard. The areas where cases and asymptomatic infected people live, as well as workplaces and activities with frequent activities and high risk of epidemic spread are classified as high-risk areas. In principle, the residential area (village) is defined as a unit, and the dangerous area can be adjusted according to the results of the mobile survey.

2. Prevention and control measures. Implement closed control measures, during which "stay at home and provide on-site service". If new infected persons are found during the containment period, the local joint prevention and control mechanism will organize risk judgment, and the containment time of the original containment area can be extended in whole or in part according to the requirements of "one area, one policy".

3. Raise the flag. There was no new infection for 7 consecutive days, and all the people in the risk area were negative after completing a round of nucleic acid screening on the 7 th day, which was reduced to a moderate risk area; For three consecutive days, no new infections were reduced to low-risk areas.

(2) Medium risk area

1. division standard. Areas such as workplaces and activity places where cases and asymptomatic infected people stay and flow for a certain period of time, which may have the risk of epidemic spread, are classified as medium-risk areas, and the scope of risk areas is defined according to the results of flow investigation and judgment.

2. Prevention and control measures. During the implementation of control measures, "people don't leave the area, they take things at the wrong peak".

3. Raise the flag. There was no new infection for 7 consecutive days, and all the people in the risk area were negative after completing a round of nucleic acid screening on the 7 th day, which was reduced to a low-risk area.