This is an infectious disease modeling study on quantifying the magnitude of infectiousness from asymptomatic cases in Wuhan, China during COVID-19 outbreak. The study was conducted by building a deterministic compartmental SEIR (Susceptible, Exposed, Infectious, Recovered) model with parameters reflecting the reality situation in Wuhan from the start of COVID-19 outbreak to subsequent pandemics. It also considerated the effects of city lockdown and other control measures during the outbreak in Wuhan. The disease model is shown as follow:
All population in Wuhan who never be infected by SARS-Cov-2 would be considered as susceptible. People who start to be infected would go to exposed phase at first which shows no symptoms of COVID-19 and still be contagious.
To mimic the real COVID-19 development along with time in Wuhan, this model is fitted with a series of parameters reflecting what have truly happened in Wuhan from the beginning of the COVID-19 transmission. Several parameters vary in different time periods due to the strict quarantine measures conducted in Wuhan after the outbreak of COVID-19. The specific value and detail of each parameter is shown on the table below:
After fitting the report data of cumulated cases in Wuhan, the fraction of asymptomatic infectiousness compared to symptomatic infectiousness is estimated from 0.45 to 0.55. The true curve of cumulated cases in Wuhan should be not as steep as the curve generated by reported data and possibly sitting around the 2 curves generated by these 2 simulations, because on February 12, 2020 there was a surged increase on the incidence which was more than 13000 cases because of the changing criteria of case inclusion. Actually, the large amount of incident cases from this date should be distributed among the previous dates to account for the fact of incidence development.
