Evolving Epidemiology and Impact of Non-pharmaceutical Interventions on the Outbreak of Coronavirus Disease 2019 in Wuhan, China

Chaolong Wang; Li Liu; Xingjie Hao; Huan Guo; Qi Wang; Jiao Huang; Na He; Hongjie Yu; Xihong Lin; An Pan; Sheng Wei; Tangchun Wu

We extended the classic SEIR model to account for population movement, unascertained cases, and quarantine by hospitalization ( Fig. 2 and Supplementary Methods). We chose to analyze data from January 1, 2020, when the Huanan Seafood Market was closed. We assumed a constant population size of 10 million of Wuhan with equal daily inbound and outbound travelers (500,000 for January 1-10, 800,000 for January 11-22 due to Chunyun, and 0 afterwards due to cordon sanitaire since January 23). 9 We divided the population into six compartments including susceptible individuals, latent cases, ascertained cases, unascertained cases, hospitalized cases, and removed individuals. Here, unascertained cases included asymptomatic cases and those with mild symptoms who could recover without seeking medical care and thus were not reported to authorities. We assumed only those seeking medical care would be reported and quarantined by hospitalization. Dynamics of these six compartments across time were described by ordinary differential equations (Supplementary Methods), along with the key parameters. The daily case data were assumed to the Poisson regression under the SEIR model. Considering the impacts of major interventions, we assumed that the transmission rate and ascertainment rate were the . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.