In this paper,with the method of epidemic dynamics,we assess the spread and prevalence of COVID-19 after the policy adjustment of prevention and control measure in December 2022 in Taiyuan City in China,and estimate t...In this paper,with the method of epidemic dynamics,we assess the spread and prevalence of COVID-19 after the policy adjustment of prevention and control measure in December 2022 in Taiyuan City in China,and estimate the excess population deaths caused by COVID-19.Based on the transmission mechanism of COVID-19 among individuals,a dynamic model with heterogeneous contacts is established to describe the change of control measures and the population's social behavior in Taiyuan city.The model is verified and simulated by basing on reported case data from November 8th to December 5th,2022 in Taiyuan city and the statistical data of the questionnaire survey from December 1st to 23rd,2022 in Neijiang city.Combining with reported numbers of permanent residents and deaths from 2017 to 2021 in Taiyuan city,we apply the dynamic model to estimate theoretical population of 2022 under the assumption that there is no effect of COVID-19.In addition,we carry out sensitivity analysis to determine the propagation character of the Omicron strain and the effect of the control measures.As a result of the study,it is concluded that after adjusting the epidemic policy on December 6th,2022,three peaks of infection in Taiyuan are estimated to be from December 22nd to 31st,2022,from May 10th to June 1st,2023,and from September 5th to October 13th,2023,and the corresponding daily peaks of new cases can reach 400000,44000 and 22000,respectively.By the end of 2022,excess deaths can range from 887 to 4887,and excess mortality rate can range from 3.06%to 14.82%.The threshold of the infectivity of the COVID-19 variant is estimated 0.0353,that is if the strain infectivity is above it,the epidemic cannot be control with the previous normalization measures.展开更多
In 2020,an unexpectedly large outbreak of the coronavirus disease 2019(COVID-19)epidemic was reported in China's Mainland.As we known,the epidemic was caused by imported cases in other provinces of China except fo...In 2020,an unexpectedly large outbreak of the coronavirus disease 2019(COVID-19)epidemic was reported in China's Mainland.As we known,the epidemic was caused by imported cases in other provinces of China except for Hubei in 2020.In this paper,we developed a differential equation model with tracing isolation strategy with close contacts of newly confirmed cases and discrete time imported cases,to perform assessment and risk analysis for COVID-19 outbreaks in Tianjin and Chongqing city.Firstly,the model behavior without imported cases was given.Then,the real-time regeneration number in Tianjin and Chongqing city revealed a trend of rapidly rising,and then falling fast.Finally,sensitivity analysis demonstrates that the earlier with Wuhan lock-down,the fewer cases in these two cities.One can obtain that the tracing isolation of close contacts of newly confirmed cases could effectively control the spread of the disease.But it is not sensitive for the more contact tracing isolation days on confirmed cases,the fewer cases.Our investigation model could be potentially helpful to provide model building technology for the transmission of COVID-19.展开更多
On December 7,2022,the Chinese government optimized the current epidemic prevention and control policy,and no longer adopted the zero-COVID policy and mandatory quarantine measures.Based on the above policy changes,th...On December 7,2022,the Chinese government optimized the current epidemic prevention and control policy,and no longer adopted the zero-COVID policy and mandatory quarantine measures.Based on the above policy changes,this paper establishes a compartment dynamics model considering age distribution,home isolation and vaccinations.Parameter estimation was performed using improved least squares and Nelder-Mead simplex algorithms combined with modified case data.Then,using the estimated parameter values to predict a second wave of the outbreak,the peak of severe cases will reach on 8 May 2023,the number of severe cases will reach 206,000.Next,it is proposed that with the extension of the effective time of antibodies obtained after infection,the peak of severe cases in the second wave of the epidemic will be delayed,and the final scale of the disease will be reduced.When the effectiveness of antibodies is 6 months,the severe cases of the second wave will peak on July 5,2023,the number of severe cases is 194,000.Finally,the importance of vaccination rates is demonstrated,when the vaccination rate of susceptible people under 60 years old reaches 98%,and the vaccination rate of susceptible people over 60 years old reaches 96%,the peak of severe cases in the second wave of the epidemic will be reached on 13 July 2023,when the number of severe cases is 166,000.展开更多
基金supported by Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(20210009)Key research project in Shanxi Province(202102130501002)+1 种基金Key project of National Natural Science Foundation of China(12231012)Key Projects of Health Commission of Shanxi Province(No.2020XM18).
文摘In this paper,with the method of epidemic dynamics,we assess the spread and prevalence of COVID-19 after the policy adjustment of prevention and control measure in December 2022 in Taiyuan City in China,and estimate the excess population deaths caused by COVID-19.Based on the transmission mechanism of COVID-19 among individuals,a dynamic model with heterogeneous contacts is established to describe the change of control measures and the population's social behavior in Taiyuan city.The model is verified and simulated by basing on reported case data from November 8th to December 5th,2022 in Taiyuan city and the statistical data of the questionnaire survey from December 1st to 23rd,2022 in Neijiang city.Combining with reported numbers of permanent residents and deaths from 2017 to 2021 in Taiyuan city,we apply the dynamic model to estimate theoretical population of 2022 under the assumption that there is no effect of COVID-19.In addition,we carry out sensitivity analysis to determine the propagation character of the Omicron strain and the effect of the control measures.As a result of the study,it is concluded that after adjusting the epidemic policy on December 6th,2022,three peaks of infection in Taiyuan are estimated to be from December 22nd to 31st,2022,from May 10th to June 1st,2023,and from September 5th to October 13th,2023,and the corresponding daily peaks of new cases can reach 400000,44000 and 22000,respectively.By the end of 2022,excess deaths can range from 887 to 4887,and excess mortality rate can range from 3.06%to 14.82%.The threshold of the infectivity of the COVID-19 variant is estimated 0.0353,that is if the strain infectivity is above it,the epidemic cannot be control with the previous normalization measures.
基金The project is funded by the National Natural Science Foundation of China under Grants(11801398,12022113,11671241,61873154,11601292)Natural Science Foundation of Shanxi Province Grant No.201801D221024.
文摘In 2020,an unexpectedly large outbreak of the coronavirus disease 2019(COVID-19)epidemic was reported in China's Mainland.As we known,the epidemic was caused by imported cases in other provinces of China except for Hubei in 2020.In this paper,we developed a differential equation model with tracing isolation strategy with close contacts of newly confirmed cases and discrete time imported cases,to perform assessment and risk analysis for COVID-19 outbreaks in Tianjin and Chongqing city.Firstly,the model behavior without imported cases was given.Then,the real-time regeneration number in Tianjin and Chongqing city revealed a trend of rapidly rising,and then falling fast.Finally,sensitivity analysis demonstrates that the earlier with Wuhan lock-down,the fewer cases in these two cities.One can obtain that the tracing isolation of close contacts of newly confirmed cases could effectively control the spread of the disease.But it is not sensitive for the more contact tracing isolation days on confirmed cases,the fewer cases.Our investigation model could be potentially helpful to provide model building technology for the transmission of COVID-19.
基金supported by the National Natural Science Foundation of China(12022113 and 12271314)Henry Fok Foundation for Young Teachers(171002)Outstanding Young Talents Support Plan of Shanxi Province.
文摘On December 7,2022,the Chinese government optimized the current epidemic prevention and control policy,and no longer adopted the zero-COVID policy and mandatory quarantine measures.Based on the above policy changes,this paper establishes a compartment dynamics model considering age distribution,home isolation and vaccinations.Parameter estimation was performed using improved least squares and Nelder-Mead simplex algorithms combined with modified case data.Then,using the estimated parameter values to predict a second wave of the outbreak,the peak of severe cases will reach on 8 May 2023,the number of severe cases will reach 206,000.Next,it is proposed that with the extension of the effective time of antibodies obtained after infection,the peak of severe cases in the second wave of the epidemic will be delayed,and the final scale of the disease will be reduced.When the effectiveness of antibodies is 6 months,the severe cases of the second wave will peak on July 5,2023,the number of severe cases is 194,000.Finally,the importance of vaccination rates is demonstrated,when the vaccination rate of susceptible people under 60 years old reaches 98%,and the vaccination rate of susceptible people over 60 years old reaches 96%,the peak of severe cases in the second wave of the epidemic will be reached on 13 July 2023,when the number of severe cases is 166,000.
