Research On Optimal Epidemic Prevention And Control Strategy Based On Transmission Dynamic

Major outbreaks of infectious diseases not only seriously endanger human lives,but also pose a serious challenge to socioeconomic development.Corona Virus Disease 2019(COVID-19)has cumulatively infected more than 500 million cases and cumulatively killed more than6 million cases worldwide,and with the escalating mutation of COVID-19,the prevention and control of the epidemic has become more challenging.Therefore,exploring scientific and effective outbreak prevention and control strategies is not only of positive significance for the current fight against the epidemic,but also can provide reference suggestions for future responses to similar major public safety and health events.In this thesis,we first improved the classical SEIR transmission kinetic model based on the characteristics of novel coronavirus pneumonia,and obtained the epidemic data released by the Hubei Provincial Health Commission through a scrapy framework crawler,and then fitted the Hubei epidemic data to the model transmission rate,conversion rate,removal rate and other parameters by using the least squares method and Powell optimization method.Comparing the model predicted epidemic and real epidemic data,it was found that the predicted epidemic data matched well with the real epidemic data,and the model could be used for further research.Secondly,by studying the perturbation of the number of population contacts in the improved SEIR transmission dynamics model,it was found that when the number of population contacts was strictly controlled,the number of incubators and infected persons were significantly reduced and the end of the epidemic was advanced.In order to investigate the optimal crowd control strategy at the early stage of epidemic prevention and control,this thesis further introduces the optimal control principle,takes the number of population contacts as the control variable,minimizes the number of exposed persons,the number of infected persons and the cost of population control as the objective function,and combines the Pontryagin minimization principle to obtain the path of optimal crowd control strategy over time.Under the optimal population control strategy,not only the epidemic is controlled more effectively,but also the social epidemic prevention cost brought about under this strategy can be minimized.Finally,in order to explore the optimal vaccination strategy in the late stage of epidemic prevention and control after vaccine intervention,this thesis establishes the Hamilton-Jacob-Bellman equation(HJB equation)with the vaccination rate as the control variable and the number of incubators,the number of infected persons and the minimization of vaccination prevention and control costs as the objectives,calls the ipopt solver in Python,and uses the numerical solution method to obtain the optimal vaccine path of vaccination strategy over time.This thesis shows that the improved SEIR transmission dynamics model fits the COVID-19 epidemic in Hubei Province well and can be applied to the current COVID-19 epidemic study;the number of population contacts from the perturbation model reveals that a strict population control strategy can effectively reduce the number of susceptible and infected persons and contain the development of the epidemic;under the consideration of social epidemic prevention costs,the optimal The optimal crowd control strategy,taking into account the social cost of epidemic prevention,suggests that a "strict first,then slow" strategy should be followed,i.e.,strict crowd control at the beginning of the epidemic,and slow and orderly crowd control after the epidemic is effectively controlled to gradually restore social order;the epidemic is further contained after the intervention of COVID-19 vaccine,and the optimal vaccination strategy,taking into account the cost of vaccination,suggests that the epidemic should be further contained.The optimal vaccination strategy suggests that vaccination should be carried out at high intensity for the whole population,especially for those with high mobility and high per capita exposure,and that the protection rate of the vaccine for various groups of people needs to be further improved due to the persistence of COVID-19.