Dynamics Research Of COVID-19 Transmission Considering The Decline Of Antibody Level And Control Measures

The COVID-19 epandemic has spread worldwide,posing a serious threat to people’s health and life safety.At present,COVID-19 infection has entered a low level,but the epidemic is far from over,so it is still of great significance to study the transmission mechanism of COVID-19.After COVID-19 infection,people will get antibodies,and vaccination will also produce antibodies,but the antibody level decreases with time.The effective evaluation of the relationship between the decrease in antibody levels and the spread of the epidemic is a very worthwhile issue to study.Vaccination and appropriate prevention and control measures can have an impact on blocking the spread of the epidemic.How to effectively evaluate the impact of these measures on the spread of the epidemic is also a very important issue.Therefore,this study mainly analyzes the impact of antibody level,vaccination and prevention and control measures on the spread of the epidemic by establishing a deterministic dynamic model of COVID-19 transmission.The main content is as follows:Study on the dynamics of COVID-19 transmission caused by the decline of antibody level and vaccination.Based on the epidemic data in England from September 1 to October31,2020,and considering the sustained decrease in antibody levels in COVID-19 restorers,a SEIR model is established,and the dynamic parameters of the SEIR model are fitted.On this basis,a SEIRV model considering vaccination is established,analyzing the impact of different vaccination rates and vaccine failure rates on the development of the epidemic in England.The peak always decreases with the decrease of vaccine failure rates,and the peak time is related to a critical value.When the vaccine failure rate is less than this critical value,the peak time advances with the decrease of vaccine failure rate;when the vaccine failure rate is greater than this critical value,the peak time is delayed as the vaccine failure rate decreases.Regardless of whether the vaccine failure rate is greater than the critical value,effective vaccination will not cause the medical system to collapse and will allow sufficient time to respond to the outbreak of the epidemic.Therefore,it is very important to improve the effectiveness of vaccines on the basis of increasing vaccination rates.Study on the dynamics of epidemic transmission within closed-loop management during the Winter Olympics.In order to study the epidemic situation within the closed-loop management during the Beijing 2022 Olympic Winter Games,an improved dynamics model of Omicron transmission is established considering the two subgroups of domestic and foreign personnel,and the basic regeneration number of the model is calculated.Analyze the impact of the proportion of exposed persons being detected（ρ）,the degree of admixture between the two populations（θ）and the initial value of the exposed among inbound personnel（E₁（0））on the number of quarantined persons.Compared with the parameters（ρ）and（θ）,the initial value of the exposed among inbound personnel（E₁（0））has a more obvious impact on the model.This shows that for the epidemic prevention and control within the closed-loop management of the Beijing 2022 Olympic Winter Games,the most effective method is to control the initial value of the exposed among inbound personnel.Study on the evaluation of epidemic prevention and control measures based on SEIR model.In order to retrospectively evaluate the epidemic situation caused by Omicron in Shanghai and Jilin,and find the basis for the epidemic prevention and control policy,the dynamics model considering the quarantine of close contacts is established.The number of daily new positive cases in Shanghai and Jilin are fitted by using known parameters,and the scale of the epidemic in the two cities under different prevention and control conditions is analyzed by simulating the number of daily new quarantined people.For Shanghai,the initial value of the exposed people has the most obvious impact on the daily new quarantined people,which requires the relevant departments to detect the potential virus carrier in the population at the initial stage as much as possible.For Jilin,controlling the initial value of infected people at a lower level plays a more significant role in controlling the scale of the epidemic,which requires relevant departments to take strict control measures when the initial number of infected persons is low.