Assessing the Global Tendency of COVID-19 Outbreak

Qinghe Liu; Zhicheng Liu; Junkai Zhu; Yuhao Zhu; Deqiang Li; Zefei Gao; Liuling Zhou; Junyan Yang; Qiao Wang

(1) Because the difference of infectivity between the exposed and the infectious population is unknown, both groups of E and I are set to follow the same coefficient β to represent the average infection level of COVID-19. (2) In the predicted time scale, the existing influences of policies or culture of the target object will be unchanged. Transmission rate to the recovered from the exposed. where t means time, and S, E, I, R represent four different state variables, respectively. Class S represents a healthy population without virus. Once transferred to class E, it means the population has been infected until transferred to class R, recovered. The difference between group E and group I is that people in class E are in the incubation period of transmission, while people in class I have been diagnosed due to symptom detection. Formula (3.1) can be represented by the state transition diagram in Figure 1 . All parameters and physical interpretations of the model are shown in Table 1 .