Assessing the Effectiveness of the Intervention Measures of COVID-19 in China Based on Dynamical Method

The Chinese government eliminated local COVID-19 outbreaks over and over again since it was reported in Wuhan in 2019. Due to higher mortality rate than influenza, normalized interventions were implemented in different cities to contain the outbreak. However, the differences in the intensity and timeliness of the implementations lead to differences in final size of the infections. So applying mathematical method to assess the effectiveness of interventions and exploring their impact on epidemic patterns are desperately needed to provide theoretical guidance for future practical work. In this study, we construct a dynamic model to describe COVID-19 transmission and control in China by taking Xi’an, Zhengzhou and Yuzhou, as examples. We apply reported human cases to verify the model, and then apply the model to speculate transmission trend and length of concealed period of the epidemic at the initial spread phase, to estimate the range of basic reproduction number, and to define two indexes to evaluate the overall effect of the interventions. It is concluded that strengthening the precision of close contact tracing and frequency of large-scale nucleic acid testing of the general public in the early days are the most effective on controlling the outbreaks and reducing final size. And, large-scale nucleic acid testing for non-quarantined population is not essential if the tracking strategy is sufficiently implemented and its effect at the late stage is weaker. That can explain the fact that the epidemic situation was more severe in Xi’an, where the large-scale nucleic acid testing for non-quarantined population was not implemented promptly in the case of weaker precision of close contact tracing, which led to controlled rate to rarely keep up with transmission rate for a long time. Keywords: COVID-19, Close contact tracing, Nucleic acid testing, Dynamics, The basic reproduction number, Sensitivity analysis.