Abstract
In December 2019, the first confirmed case of pneumonia caused by a novel coronavirus was reported. Coronavirus disease 2019 (COVID-19) is currently spreading around the world. The relationships among the pandemic and its associated travel restrictions, social distancing measures, contact tracing, mask-wearing habits and medical consultation efficiency have not yet been extensively assessed. Based on the epidemic data reported by the Health Commission of Wenzhou, we analysed the developmental characteristics of the epidemic and modified the Susceptible-Exposed-Infectious-Removed (SEIR) model in three discrete ways. (1) According to the implemented preventive measures, the epidemic was divided into three stages: initial, outbreak and controlled. (2) We added many factors, such as health protections, travel restrictions and social distancing, close-contact tracing and the time from symptom onset to hospitalisation (TSOH), to the model. (3) Exposed and infected people were subdivided into isolated and free-moving populations. For the parameter estimation of the model, the average TSOH and daily cured cases, deaths and imported cases can be obtained through individual data from epidemiological investigations. The changes in daily contacts are simulated using the intracity travel intensity (ICTI) from the Baidu Migration Big Data platform. The optimal values of the remaining parameters are calculated by the grid search method. With this model, we calculated the sensitivity of the control measures with regard to the prevention of the spread of the epidemic by simulating the number of infected people in various hypothetical situations. Simultaneously, through a simulation of a second epidemic, the challenges from the rebound of the epidemic were analysed, and prevention and control recommendations were made. The results show that the modified SEIR model can effectively simulate the spread of COVID-19 in Wenzhou. The policy of the lockdown of Wuhan, the launch of the first-level Public Health Emergency Preparedness measures on 23 January 2020 and the implementation of resident travel control measures on 31 January 2020 were crucial to COVID-19 control.
Highlights
In December 2019, initially isolated cases of pneumonia due to infection with a novel coronavirus progressed to an outbreak in Wuhan, Hubei, China
The results show that the modified SEIR model can effectively simulate the spread of COVID-19 in Wenzhou
Reconstruction of COVID-19 spread based on the modified SEIR
Summary
In December 2019, initially isolated cases of pneumonia due to infection with a novel coronavirus progressed to an outbreak in Wuhan, Hubei, China. On 20 January 2020, the National Health Commission of the People’s Republic of China (NHC) confirmed that this novel coronavirus could spread from person to person [1]. On 24 January, during the Lunar New Year, the high travel volume and mass gatherings further increased the risk of virus transmission. To combat public health emergencies from local transmission, on 23 January 2020, all public transport and air travel access in Wuhan was suspended, 11 million residents were quarantined, and Lunar New Year celebrations were cancelled in many cities in China. Under a series of control measures, the spread of the virus was quickly managed. Since 16 February, the number of new cases in China has gradually decreased
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