Because there has been a precedent of simultaneous aircrew infection, the epidemic has strengthened the control of simultaneous aircrew on the basis of centralized isolation of close contacts and sub-close contacts. If big data receives a call from the health treasure pop-up window or neighborhood Committee after judgment, it must be tested for nucleic acid first, and then enter the home period.
Spatio-temporal intersection refers to people who stay in the same spatio-temporal grid (range of 800 m * 800 m) with virus-infected people for more than 10 minutes within 14 days, or people who have crossed with virus-diagnosed patients. After the green code is changed to the yellow code, for example, in Suzhou, it is necessary to isolate at home for three days in a row, and go to the designated isolation hospital for nucleic acid twice within three days, and both nucleic acids are negative, so that the yellow code can be changed back to the green code.