基于改进SEIR模型的新冠肺炎疫情沿交通线路传播机制

Transmission mechanism of COVID-19 epidemic along traffic routes based on improved SEIR model

考虑了新冠肺炎通过接触和飞沫传染、在潜伏期具有传染性等特性,结合交通工具空间狭小、环境密闭的特点,基于SEIR模型,建立了考虑交通工具内病毒密度、乘客之间接触率与感染率、乘客乘坐时间等因素的交通工具内部疫情传播模型;基于交通工具内部疫情传播形式,考虑交通工具在多个停靠站点上下乘客的过程将疫情传播到非疫区,建立了基于人口迁徙的疫情沿交通线路传播的模型;利用建立的2个模型,分析了疫情沿交通线路传播机制,研究了武汉人口迁徙指数与确诊人数的关系,并模拟了疫情沿高铁线路传播的过程。研究结果表明:各省、市级累计确诊人数与人口迁徙指数有着较强的正相关性,表明交通对疫情传播具有一定的助推作用,在交通运输工具内有可能造成一定数量乘客被感染;依据潜伏期的推后效应,在一定程度上解释了除武汉之外中国其他各省市区在2020年1月31日至2月5日每日新增确诊人数处于高峰状态;采取隔离与降低乘客上座率等措施减少乘客相互之间接触机会,可以有效降低乘客被感染风险,且效果显著好于通风和消毒措施。可见,为了合理控制疫情沿交通线路传播,在交通运输工具内应以降低上座率,加大乘客之间的乘坐距离,降低相互接触率等措施为主,辅以增加通风和消毒措施。

The characteristics of COVID-19,which is transmitted by contact and droplets and is infectious in the incubation period,were considered.Combined with the narrow space and airtight environment of the vehicle and based on SEIR model,the vehicle internal epidemic transmission model was established considering the factors of virus density,contact and infection rate among passengers,and travel time.Based on the internal epidemic transmission form in the vehicle,the epidemic transmission to the non-epidemic area in the process of the vehicle loading and unloading passengers at multiple stops was considered,and a model of epidemic spread along traffic routes based on population migration was established.The transmission mechanism of the epidemic along traffic routes was analyzed using the two models.Based on the population migration index and confirmed cases in Wuhan,the relationship between confirmed cases and population migration index was analyzed,and the transmission process of the epidemic along the high-speed railway was simulated.Research result shows that the cumulative confirmed cases of each provincial and municipal level have a strong positive correlation with the population migration index,indicating that transportation has a certain role in promoting the spread of the epidemic.There may be some passengers infected within the vehicle when there are infectives.With the backward effect of incubation period,to some extent,it explains that except for Wuhan,the number of newly confirmed cases in urban areas of other provinces in China was at a peak on January 31 to February 5 in 2020.The measures such as isolation and reducing passenger occupancy to reduce the contact between passengers can effectively reduce the infection risk of passengers,and the effect is significantly better than the ventilation and disinfection measures.Therefore,in order to reasonably control the spread of the epidemic along traffic routes,some measures should be taken to reduce the occupancy rate,increase the distance between passengers and reduce the contact rate,supplemented by the measures to increase ventilation and disinfection.