SEIR Transmission dynamics model of 2019 nCoV coronavirus with considering the weak infectious ability and changes in latency duration

Pengpeng Shi; Shengli Cao; Peihua Feng

The rapid spread of 2019-noV pneumonia around the world poses a major threat to the closely connected and interdependent world today. The reproductive number R refers to the average number of secondary cases generated from primary cases, and has become a key quantity to determine the intensity of interventions needed to control epidemics [2] . On January 29, 2020, Li et al conducted a study of the first 425 confirmed cases in Wuhan, showing that the R of 2019-nCoV was 2.2, and revealed that person-to-person transmission occurred between close contacts [3] . On January 26, 2020, new research shows that the reproductive ratio of 2019-nCoV is 2.90, which is higher than the 1.77 SARS epidemic [4] 。In the absence of comprehensive treatments or vaccines, China has adopted the most effective isolation prevention and control measures to isolate patients diagnosed with 2019-nCoV to control the spread of infection, but the number of 2019-nCoV infections has far exceeded that of SARS epidemics. Existing basic research results and actual situation of epidemic spread have shown that 2019-nCoV has a higher pandemic risk than the outbreak of SARS in 2003 [4] 。 This paper discusses the feasibility of using the deterministic model of the transmission dynamics model of infectious diseases to assess the development of the 2019-nCoV epidemic in China. Some researchers have tried to study and evaluate the development trend of the 2019-nCoV pneumonia epidemic through the transmission dynamics. On Jan 24, 2020, British scholars Read et al [5] estimated that the number of 2019-nCoV infection cases in Wuhan would reach 190000 on Feb 4, which obviously overestimated the development trend of the epidemic. On Jan 31, 2020, Wu et al [6] , scholars from Hong Kong, China, predicted that the number of infections in Wuhan on Jan 25 exceeded 75815, which also obviously overestimated the spread of the epidemic. Chinese scholars Shen et al. [7] used dynamics models to predict the peak time and scale of the epidemic, and estimated that the peak number of infections was less than 20,000, which was lower than the raw data released on Feb 10. Chinese scholars Xiao et al. [8] established a transmission dynamic model with considering intervention strategies such as close tracking and quarantine. Based on their model, scholars predicted that the epidemic would reach its peak around Feb 5 [8] , which made an early estimation of the peak time of the epidemic. In summary, although some researchers have carried out research on the transmission dynamics of the 2019-nCoV pneumonia epidemic, the real epidemic development has far deviated from the prediction results of previous studies.