病毒学报

2019年12月以来,湖北省武汉市部分医院陆续发现了多例不明原因肺炎病例,现已证实为新型冠状病毒肺炎(Coronavirus disease 2019,COVID-19)。全国各地采取了前所未有的措施,大力开展疾病救治和防疫工作。本文收集中国国家卫生健康委员会公布的官方统计数据预测疫情走向。传统SEIR模型中仅考虑病例和处于潜伏期的感染者,病例具有传染性而潜伏者无传染性;事实上,新冠肺炎确诊患者在医院中隔离无法对外界易感人群造成感染,有研究表明处于潜伏期的感染者可能具有传染性。因此,本研究提出了改进的传染病传播模型—ISEIR,将患者分为未收治的发病患者(具有传染性)和已收治的确诊患者(不考虑传染性),并考虑处于潜伏期的感染者具有传染性;以历史数据动态拟合模型参数,来摆脱固定参数的局限性。在数据预处理中根据每日有效再生数的概率分布将2020年2月12至14日这三天的临床诊断数据进行预处理,摊入到前期数据中。疫情分成全国(湖北省外)和湖北省两大区域分别进行探讨,通过新模型ISEIR预测今后疫情的进一步发展,并计算每日的有效再生数变化。结果显示,湖北省的有效再生数从3.108逐渐降低,2020年4月19日所有患者将全部治愈出院,累计确诊患者为66 487人;全国(湖北省外)的初始有效再生数为1.929,小于湖北省,2020年3月26日所有患者全部治愈,累计确诊患者13 270人。从结果中可以发现,在严格的防控措施下疫情得到了有效抑制,验证了目前防控措施的有效性,但仍需要防止复工潮引起的疫情反弹。

Coronavirus disease 2019(COVID-19) spread initially from Wuhan(Hubei Province,China) in December 2019 through China,but is now a pandemic. Unprecedented steps have been taken throughout China to vigorously carry out disease treatment and epidemic prevention. Official statistics published by the National Health Commission of the People's Republic of China were collected to predict the trend of the epidemic. In the traditional Susceptible,Exposed,Infectious,Recovered(SEIR) model,only infectious patients and noninfectious latent patients are considered. However,COVID-19-diagnosed patients cannot infect the susceptible population because they have been isolated in hospitals,whereas latent patients may be infectious. Based on this information,we propose an improved model of infectious-disease transmission:"ISEIR". In ISEIR,patients are divided into outpatients(with infectivity)and inpatients(infectivity is not considered). Preclinical patients who are infectious are also considered. ISEIR fits model parameters dynamically with historical data to exclude the limitations of fixed parameters. The data of patients diagnosed early with COVID-19 in Hubei Province,China was seriously distorted. Therefore,according to the probability distribution of the daily basic reproduction number(R₀),the clinical-diagnosis data of February 12–14 were preprocessed and spread into previous data to correct distortion of previous data. The epidemic situation was divided into two regions:the whole country(excluding Hubei Province,China)and Hubei Province,China. The new ISEIR predicts further development of the future epidemic,and calculates the change in daily R₀. Results revealed that the R₀ of Hubei Province,China has reduced gradually from 3.108. All patients will be cured and discharged from hospital around April 19.The initial R₀ of China(excluding Hubei Province)was 1.929,and all patients will be cured around March 26.Results showed that the epidemic has been suppressed effectively under strict prevention-and-control measures.It is also necessary to prevent rebound of the epidemic situation caused by the resumption of employment.