First, the nucleic acid test showed that the case was a recent infection, and the viral load in the body was still relatively high. Secondly, both the hotel where the two cases lived and the Japanese food store where they ate found that the environment was positive, indicating that they were in the detoxification period and were more likely to spread. The third point is that although these two cases have not been in Guangzhou for a long time, they have a wide range of activities. In a day or so, they have been involved in 14 key places in Tianhe, Panyu, Nansha and Huadu, and there are many potential contact points. Zhang said that in view of this situation, Guangzhou immediately adopted temporary management measures such as sealing and controlling key places, and at the same time classified reminders and epidemic prevention management for relevant personnel according to risk levels. (Guangming Daily full media reporter Wu Chunyan Zhong Wang Yao)