天津市5例新型冠状病毒肺炎无症状感染者的流行病学调查

Epidemiological investigation of five asymptomatic COVID-19 cases in Tianjin

目的通过对天津市新型冠状病毒肺炎(COVID-19)无症状感染者进行调查和分析,了解无症状感染者的流行病学特征、发现途径及可能的感染性,为COVID-19的防控提供更多流行病学证据和经验。方法通过主动监测发现确诊COVID-19无症状感染者,运用描述性研究方法对5例无症状感染者进行流行病学特征分析。结果截止2月19日天津市COVID-19无症状感染者比例为3.85%(5/130)。女性2例、男性3例。3例为与确诊病例共同生活感染,2例为与确诊病例近距离密切接触感染。3例通过密切接触者主动筛查发现,1例通过聚集性疫情调查中开展的主动检测发现,1例通过COVID-19确诊病例传染源追踪对暴露人群的主动检测发现。与无症状感染者密切接触后也可能成为新的感染者。结论应通过加强密切接触者管理和筛查等方式及时发现COVID-19无症状感染者,调整无症状感染者的密切接触者判定时间。COVID-19无症状感染者是COVID-19疫情防控的难点,对其流行情况需进行进一步调查研究,以指导COVID-19疫情的防控。

Objective To investigate and analyze the asymptomatic cases of Corona Virus Disease 2019(COVID-19)in Tianjin,understand the epidemiological characteristics,discovery route and possible infectivity of asymptomatic cases,and provide more epidemiological evidence and experience for the prevention and control of COVID-19.Methods Asymptomatic COVID-19 cases were confirmed by active surveillance.Descriptive research method was used to analyze the epidemiological characteristics of five asymptomatic COVID-19 cases.Results Asymptomatic COVID-19 cases accounted for 3.85%(5/130)of the total confirmed COVID-19 cases reported in Tianjin as of February 19,2020.There were two females and three males in the five asymptomatic COVID-19 cases.Three asymptomatic COVID-19 cases were infected by living with the confirmed case,and two asymptomatic COVID-19 cases were infected by close contact with the confirmed case.Three cases were detected by active screening of close contacts,one case was detected by active surveillance in an outbreak investigation of COVID-19,and one case was detected by active surveillance of the exposed population by infection source tracing of the confirmed COVID 19 case.Close contact with asymptomatic COVID-19 cases could also infection.Conclusion It is necessary to strengthen the management and screening of close contacts of COVID-19 cases for the timely detection of the asymptomatic infection,and adjust the time for identifying the close contacts of the asymptomatic individuals.Asymptomatic infection poses difficulty for the prevention and control of COVID-19.Further investigation and research on epidemiological characteristics of asymptomatic infection is needed to guide the prevention and control of COVID-19.