Analysis of COVID-19 by Discrete Multi-stage Dynamics System with Time Delay

Coronavirus disease 2019(COVID-19) has broken out worldwide. Up to Apr.21, 2020, more than 2.45 million confirmed cases have been diagnosed, and more than 0.17 million deaths have been reported. Based on the development process of China's epidemic, this paper proposes an improved discrete-time multi-stage time-delay dynamic model to extract the transmission characteristics of epidemic, the impact of prevention and control interventions (prevention and control intervention effect) and the impact of medical resource availability, and establishes an empirical transmission dynamics method of COVID-19 analysis.Among them, the experience extraction is based on the model and the epidemic data released by World Health Organization(WHO), and realized by parameter inversion. Furthermore, by using the proposed method, this paper analyzes the epidemic stages in Italy, Spain, Germany and the United States, predicts the possible trend of epidemic situation in different countries under different measures, and gives suggestions on rapid control. Analysis results show that the China's epidemic has been basically controlled, Spain, Germany and Italy have reached the peak, and the United States is in a rapid growth period. According to the empirical transfer dynamics method, Spain, Germany and Italy should continue to adhere to the current prevention and control intervention mode, and the United States should intensify the efforts of prevention and control and make the epidemic enter the controllable stage as soon as possible.