Epidemiological analysis on 1052 cases of COVID-19 in epidemic clusters/ 1052例新型冠状病毒肺炎聚集性病例流行病学特征分析

Objective To understand the epidemiological characteristics of the cases of COVID-19 epidemic clusters, and explore the influence of family factors and social factors such as group activities on the spread of the disease Methods The data of cases of COVID-19 epidemic clusters from 19 January, 2020 to 25 February, 2020 were collected from the official platforms of 36 cities in 6 provinces in China Descriptive statistical methods, χ2 test and curve fitting were used to analyze the epidemiological characteristics of the clustered cases Results By 25 February, 2020, the data of 1 052 cases in 366 epidemic clusters were collected In these clustered cases, 86 9%(914/1 050) occurred in families Among the 1 046 cases with gender information, 513 were males (49 0%) and 533 were females (51 0%) The cases were mainly young adults between 18 and 59 years old, accounting for 68 5% (711/1 038) In the 366 epidemic clusters , the clusters in which the first confirmed cases with the history of sojourn in Wuhan or Hubei accounted for 47 0%(172/366) From 19 January to 3 February, 2020, the first confirmed cases with Wuhan or Hubei sojourn history accounted for 66 5% From 4 to 25 February, the first confirmed cases who had Wuhan or Hubei sojourn history accounted for only 18 2% The median of interval between the first generation case onset and the second generation case onset was 5 (2-8) days The median of onset- diagnosis interval of the initial cases was 6 (3-9) days, and the median of onset-diagnosis interval of the secondary cases was 5 (3-8) days Conclusions Epidemic clusters of COVID-19 were common in many cities outside Wuhan and Hubei Close contact in family was one of the main causes for the spread of household transmission of the virus After 4 February, the epidemic clusters were mainly caused by the first generation or second generation cases in local areas, and the time for diagnosis became shorter