基于感染力与免疫作用的新型冠状病毒肺炎疫情传播模型

Transmission Model of COVID-19 Pandemic Based on Infectivity and Immunity

目的严重急性呼吸综合征冠状病毒2(SARS-CoV-2)变体往往具有更强的感染力与免疫逃逸能力,目前出现的SARS-CoV-2变体种类繁多,疫情评估与防控形势严峻。本文希望通过建立模拟病毒传染的理论模型,对SARS-CoV-2及其变体引起的疫情进行追踪与预测,并对它们的综合传染性进行评估。方法根据方格传染病模型,对传染持续时间和群体免疫作用的相互关系进行推导,并在此基础上建立了新型冠状病毒肺炎(COVID-19)疫情感染传播的普遍理论模型,提出感染力参数A和免疫作用参数B,将传染时间与感染人数的复杂关系公式化,用于预测感染日变曲线。还引入了突变株综合传染性参数A/B^(2/3),用以定量比较各突变株的综合传染能力,并对感染参数A和B不与地域因素相关的猜想进行了验证。结果通过COVID-19疫情传播的理论模型,对病毒步行次数与传染时间做出了较为精准的预测。通过对突变株感染能力与电性变化的分析,指出了突变株传染性和突变残基电性变化的内在联系。分析了突变株的参数变化,定量比较了各突变株的综合传染能力,得出了综合传染性排行。还验证了参数A和B只与病毒自身性质、病毒与人体共存的性质相关,而与地域无关的猜想,并对各爆发地域的防疫水平进行了评估与比较。结论本文建立了COVID-19疫情传播的理论模型,在预测疫情持续时间、每日新增感染人数与评估病毒感染力、免疫逃逸能力、综合传染性、地域防疫水平方面具有一定作用,还根据病毒变异可能导致的参数变化给出了防疫注意事项与相关对策的建议。

Objective Many mutant strains of SARS-Co V-2 have stronger infectivity and immune escape ability.The situation of epidemic evaluation,prevention and control is serious.The aim of the present paper is to track and predict the infectious transmission of COVID-19 through a theoretical model.Methods Based on the grid epidemic model,this paper discussed the relationship between the duration of infection and the effect of group immunity,and on this basis,established the theoretical model of infection transmission of COVID-19.The infectivity parameter A and the immune effect parameter B are introduced to predict the daily variation curve of infection.The parameter A/B^(2/3)can be used to quantitatively compare the comprehensive infectivity of each mutant,and we also test the conjecture that the infection parameters A and B are not related to regional factors.Results Through the theoretical model of infection transmission of COVID-19,the infectious time was accurately predicted.By analyzing the infectivity and electrical changes of mutant strains,the internal relationship between the infectivity of mutant strains and the electrical changes of mutant residues was pointed out.The parameter changes of mutants were analyzed,and the comprehensive infectivity of each mutant was quantitatively compared.We also verified the conjecture that parameters A and B are only related to the nature of the virus itself and the coexistence of the virus and the human body,but not related to the region where the disease occurs and evaluated and compared the epidemic prevention level of each outbreak region.Conclusion This paper established a theoretical model of infection transmission of COVID-19,which can predict the duration of the epidemic,the number of new infections per day,and evaluate the infectivity of the virus,immune escape ability,comprehensive infectivity,and regional epidemic prevention level.It can also give some suggestions on epidemic prevention countermeasures according to the possible parameter changes caused by virus variation.