Early transmission dynamics of COVID-19 in China based on an epidemic model

  Objective  To simulate the full-spectrum dynamics of coronavirus disease 2019 (COVID-19) in China between 2 December 2019 and 8 April 2020 by using an epidemic dynamics model, and evaluate the impact of intervention measures on the epidemic spread.

  Methods  Based on the incidence data of COVID-19 reported to the infectious disease reporting system of Chinese Center for Disease Control and Prevention, a dynamic model was established.

  Results  The traffic control measures implemented in China reduced the R₀ of COVID-19 from 4.82 (95% confidence interval ( CrI): 4.81−4.83) in the early stage of the epidemic to 1.13 (95% CrI: 1.11−1.16). Centralized isolation and mass nucleic acid testing further reduced the R₀ to 0.31 (95% CrI: 0.30−0.32). The model estimated that the detection rate of asymptomatic infections was 54.7% (95% CrI: 45.7%−65.3%). Increasing the detection rate of asymptomatic infections to 75% and 95%, respectively, 3.4% and 5.6% of new infections would be prevented if the prevention and control measures continued for same time. Implementing the interventions one week and two weeks early, respectively, 78.2% and 95.3% of new infections would be prevented if the asymptomatic infection detection rate maintained.

  Conclusion  Traffic control measures significantly reduced the speed of SARS-CoV-2. Centralized isolation and mass nucleic acid testing blocked the spread of SARS-CoV-2 in population. Mass nucleic acid testing in China can detect more than half of asymptomatic SARS-CoV-2 infections. Compared with increasing the detection rate of asymptomatic infections, early interventions can prevent more new infections.