ABSTRACT
Objective To fit the epidemic situation of COVID-19 in Urumqi City, Xinjiang Uygur Autonomous Region in July 2020, so as to provide the quantitative and theoretical basis for the prevention and control of epidemic. Methods A dynamical model with stage control strategy was proposed using compartmental modeling method, based on the tracking and isolation measures taken during the COVID-19 epidemic in July 2020 in Urumqi City. The nonlinear least square method was applied to fit this dynamical model by using multi-source data: The cumulative number of confirmed cases, cured cases and asymptomatic cases of COVID-19 from Health Committee of Xinjiang from July to September 2020. Results The parameters of the model were estimated as follows: The rate of diagnosis was 0.6, the infectivity coefficients of latent exposure group and asymptomatic infection group were 0.78 and 0.99 respectively, and the proportion of asymptomatic infection group was 0.4. Parameter sensitivity analysis showed that increasing close tracking and isolation and reducing contact could effectively control the number of new confirmed cases. Conclusion The results show that the model has good fitting effect with the actual data;asymptomatic infection is more infectious;the trend of daily effective reproduction number shows that the government control measures are appropriate with great effect;the relevant departments should increase the close tracking and isolation, and continuously emphasize that reducing contact can effectively control the epidemic of COVID-19.