重庆市新型冠状病毒感染疫情流行病学特征及其参数与防控措施评估(2020年)

Epidemiological characteristics of COVID-19 in Chongqing and its parameter estimation and evaluation of prevention and control measures(2020)

目的了解重庆市2020年度SARS-CoV-2感染者流行病学特征,并估计该阶段疫情传播的重要流行病学参数,探究防控措施对新发流行病传播的影响。方法回顾性收集重庆市卫生健康委员会和重庆市疾病预防控制中心2020年重庆市SARS-CoV-2感染者的数据,采用描述性统计分析方法,对疾病进行流行病学特征分析,构造似然函数,并根据Akaike信息准则估计了潜伏期的最优概率分布。最后基于极大似然思想和贝叶斯框架对基本再生数、有效再生数进行了估计。结果重庆市于2020年1月1日出现首例病例,发病高峰在1月24—26日,2月21日之后无新发病例。渝东北片区地区发病率最高(3.28/10万)。发病人群男女性别比为1.10∶1,总体发病率男性(1.86 /10万)稍高于女性(1.73 /10万)。确诊病例中占比最多的年龄组为45~50岁(91例,91/576),其次是50~55岁(71例,71/576)。潜伏期的最优概率分布为伽马分布,估计均值为7.22 d。重庆市COVID-19疫情初始阶段的基本再生数估计为2.68(2.04,3.44),有效再生数的变化趋势与防控策略的实施密切相关。结论重庆市2020年1—2月全市COVID-19流行曲线呈起病急、收尾快的特点。尽管疫情具有较强的传播性,但定量和定性分析均表明政府采取防控措施及时有效,为将来新发突发传染病防控积累了经验。

Objective To understand the epidemiological characteristics of COVID-19 cases in Chongqing in 2020,and to estimate the important epidemiological parameters of epidemic transmission at that stage,so as to explore the impact of prevention and control measures on the spread of emerging epidemics.Methods Based on the retrospective data of COVID-19 cases in Chongqing in 2020 from Chongqing Municipal Health Commission and Chongqing Municipal Center for Disease Control and Prevention,descriptive statistical analysis method was used to analyze the epidemiological characteristics of the disease.Then,the likelihood function was constructed and the optimal probability distribution of the incubation period was estimated according to the Akaike information criterion.The basic reproduction number and effective reproduction number were estimated based on the maximum likelihood principle and Bayesian framework.Results The first case of COVID-19 in Chongqing appeared on January 1,2020,with the peak of infection from January 24 to January 26.After February 21,no new cases were reported.The highest incidence rate was observed in the northeastern region of Chongqing(3.28 per 100000).The male-to-female ratio was 1.10:1.The overall incidence rate among males(1.86 per 100000)was slightly higher than that among females(1.73 per 100000).The age group with the highest proportion of confirmed cases was 45-50 years old(91 cases,91/576),followed by the 50-55 age group(71 cases,71/576).The optimal probability distribution in the incubation period was gamma distribution,with an estimated average of 7.22 days.The estimated basic reproduction number in the early stage of COVID-19 epidemic in Chongqing was 2.68(2.04,3.44),and the trend of effective reproduction number was closely related to the implementation of prevention and control strategies.Conclusions The COVID-19 epidemic in Chongqing from January to February 2020 exhibited a rapid onset and quick decline.Despite its high transmissibility,both quantitative and qualitative analyses indicate that the government's timely and effective implementation of prevention and control measures has accumulated experience for new outbreaks of infectious diseases in the future.