A stochastic SEIHR model for COVID-19 data fluctuations

2021

Preprint

To date, over 182 million people on infected with COVID-19. It causes more 3.9 millions deaths. This paper introduces a symptomatic-asymptomatic-recoverer-dead differential equation model (SARDDE). It gives the conditions of the asymptotical stability on the disease-free equilibrium of SARDDE. It proposes the necessary conditions of disease spreading for the SARDDE. Based on the reported data of the first and the second COVID-19 epidemics in Beijing and simulations, it determines the parameters of SARDDE, respectively. Numerical simulations of SARDDE describe well the outcomes of current symptomatic and asymptomatic individuals, recovered symptomatic and asymptomatic individuals, and died individuals, respectively. The numerical simulations suggest that both symptomatic and asymptomatic individuals cause lesser asymptomatic spread than symptomatic spread; the blocking rates of about 80% and 97.5% to the symptomatic individuals cannot prevent the spread of the first and second COVID19 epidemics in Beijing, respectively. Virtual simulations suggest that the strict prevention and control strategies implemented by Beijing government are not only very effective but also completely necessary. The numerical simulations suggest also that using the data from the beginning to the day after about 14 -- 17 days at the turning point can estimate well the following outcomes of the two COVID-19 academics, respectively. It is expected that the research can provide better understanding, explaining, and dominating for epidemic spreads, prevention and control measures.

Modelling, Simulations and Analysis of the First and Second COVID-19 Epidemics in Beijing

2021

Preprint

Summaries, Analysis and Simulations of Recent COVID-19 Epidemics in Mainland China

2022

Preprint

Background: Globally COVID-19 epidemics have caused tremendous disasters. China prevented effectively the spread of COVID-19 epidemics before 2022. Recently Omicron and Delta variants cause a surge in reported COVID-19 infections. Methods: Using differential equations and real word data, this study modelings and simulates COVID-19 epidemic in mainland China, estimates transmission rates, recovery rates, and blocking rates to symptomatic and asymptomatic infections. The transmission rates and recovery rates of the foreign input COVID-19 infected individuals in mainland China have also been studied. Results: The simulation results were in good agreement with the real word data. The recovery rates of the foreign input symptomatic and asymptomatic infected individuals are higher than those of the mainland COVID-19 infected individuals. The blocking rates to symptomatic and asymptomatic mainland infections are lower than those of previous epidemics. The blocking rate implemented between March 24-31, 2022 may not prevent the rapid spreads of COVID-19 epidemics in mainland China. For the foreign input COVID-19 epidemics, the numbers of the current symptomatic individuals and the asymptomatic individuals charged in medical observations have decreased significantly after March 17，2022. Conclusions: Need to implement more strict prevention and control strategies to prevent the spread of COVID-19 mainland infected individuals. Need to keep the present prevention and therapy measures to foreign input COVID-19 infected infections until infected individuals to be cleared.

Summaries, Analysis and Simulations of Recent COVID-19 Epidemic in Shanghai

2022

Preprint

BackgroundAfter successfully preventing the spread of five wave COVID-19 epidemics in Shanghai, Omicron and Delta variants have been causing a surge COVID-19 infection in this city recently. Summaries, analysis and simulations for this wave epidemic are important issues.MethodsUsing differential equations and real word data, this study modelings and simulates the recent COVID-19 epidemic in Shanghai, estimates transmission rates, recovery rates, and blocking rates to symptomatic and asymptomatic infections, and symptomatic (infected) individuals’ death rates. Visual simulations predict the outcomes of this wave Shanghai epidemic. It compares parallely with the recent mainland China COVID-19 epidemics (RMCE).ResultsThe simulation results were in good agreement with the real word data at the end points of 11 investigated time-intervals. Visual simulation results showed that on the day 90, the number of the current symptomatic (infected) individuals may be between 852 and 7314, the number of the current asymptomatic (infected) individuals charged in the observations may be between 10066 and 50292, the number of the current cumulative recovered symptomatic infected individuals may be between 52070 and 74687, the number of the current cumulative asymptomatic individuals discharged from the medical observations may be between 63509 and 5164535. The number of the died symptomatic individuals may be between 801 and 1226.The transmission rate of the symptomatic infections caused by the symptomatic individuals was much lower than the corresponding average transmission rate of the RMCE.The transmission rate of the asymptomatic infections caused by the symptomatic individuals was much higher than the first 90 day’s average transmission rate of RMCE.The transmission rate of the symptomatic infections caused by the asymptomatic individuals was much lower than the first 60 day’s average transmission rate of RMCE, and was much higher than the last 60 day’s average transmission rate of RMCE.The transmission rate to the asymptomatic infections caused by the asymptomatic individuals was much higher than the corresponding average transmission rate of RMCE.The last 30 days’ average blocking rate to the symptomatic infections were lower than the last 30 days’ average blocking rates of RMCEThe last 30 days’ average blocking rate to the asymptomatic infections were much higher than the last 30 days’ average blocking rate of RMCE. However the first 30 days’ average blocking rate to the asymptomatic infections were much lower than the first 30 days’ average blocking rate of RMCE.The first 37 days’ recovery rates of the symptomatic individuals were much lower than the corresponding first 70 days’ recovery rates of the symptomatic individuals of RMCE. The recovery rates between 38- and 52-days of the symptomatic individuals were much lower than the corresponding the recovery rates between 91- and 115-days of the symptomatic individuals of RMCE. The last week’s recovery rate was similar to the last week’s recovery rate of RMCE.The first 30 days’ average recovery rate recovery rate to the symptomatic individuals were much lower than the first 30 days’ average recovery rate recovery rate of RMCE. The last 30 days’ average recovery rate recovery rate of the symptomatic individuals were still much lower than the last 30 days’ average recovery rate of RMCE.ConclusionsThe last 30 days’ low blocking rates to the symptomatic infections, the first 30 day’s low blocking rates to the symptomatic infections to asymptomatic infections, the low recovery rates of the symptomatic and asymptomatic individuals, and the high transmission rate of the asymptomatic infections may be the reasons to cause the rapid spread of the recent Shanghai epidemic. It needs to implement more strict prevention and control strategies, rise the recovery rates of symptomatic and asymptomatic infections, and reduce the death rates for preventing the spread of this wave COVID-19 epidemic in Shanghai.