Modeling the emergence of COVID-19: a systems approach

In December 2019, a novel coronavirus disease (COVID-19) suddenly emerged in Wuhan, China. In March 2020, WHO declares the coronavirus outbreak a pandemic. The virus has spread quickly to all over China and most of the countries and regions within the increasing urbanization and globalization, infected more than three million people worldwide. A crucial factor that may significantly affect the spread of COVID-19 is the multiple, interactive, emergent, and complex characteristics and systems of the social systems. This paper describes a systems approach modeling and analyzing the emergence and spread of COVID-19 in urban systems, seeking to combine the multi-layer urban structure between complex infrastructure systems, human activities and policy systems. Moreover, a complex network model is built to illustrate the diffusion of the virus with or without the intervention of policy systems under the different policy intensity by the changed basic reproduction number (R0). Besides, a system dynamics model, including feedback loops and changes, is proposed to demonstrate how the COVID-19 spreads out under the interactive and interrelated characteristics and systems of the complex systems at different levels.