The epidemiological characteristics of clusters of novel coronavirus pneumonia in Chenzhou, China

Zi-Qiang Xu^1#, Zhi-Jian Wu^1#, Qiu-Bi Xu^1*. Li Fang², Xiao-Ying Cao², Wei-Hua Chen³, Shi-Zhou Li¹, Yu-Qi Ouyang¹ 

¹Department of Emergency, First People's Hospital of Chenzhou, Chenzhou 423000, China - ²Department of Infectious Disease, Second People's Hospital of Chenzhou, Chenzhou 423000, China - ³Department of Acute Infectious Disease Control and Prevention, Chenzhou Center for Disease Control and Prevention, Chenzhou 423000, China

Objective: This study was designed to analyze the characteristics of the novel coronavirus disease 2019 (COVID-19) epidemic in seven clusters in the city of Chenzhou, China, to act as a reference for the prevention and control of the COVID-19 epidemic. 

Methods: The data of confirmed COVID-19 cases reported between January 23 and February 24, 2020, were obtained from the Chenzhou infectious disease surveillance system. In line with the diagnostic criteria of the Novel Coronavirus Pneumonia Diagnosis and Treatment Plan (Sixth Edition, Trial Implementation), 33 patients in seven clusters were selected as the research subjects, and epidemiological data were collected for descriptive analysis.

Results: Between January 23 and February 24, 2020, 46 patients with COVID-19 were diagnosed in the city of Chenzhou, comprising 24 male patients and 22 female patients. The age of these patients ranged from seven months to 72 years old. The average age was 35.88 ± 17.98 and included 13 individual patients and 33 patients in seven clusters. Six clusters were exposed to the virus in Wuhan (the Wuhan group), and the other cluster was exposed to it in Shenzhen (the Shenzhen group). In the Wuhan group, the disease was spread in clusters of one family. The incubation period was 1–9 days, and the average length of hospital stay was 13.25 ± 2.67 days. Only close contacts were infected. In the Shenzhen group, three different families were infected in the same cluster. The incubation period was 11–14 days, the time of positive-to-negative conversion in the nucleic acid test was longer, and the average hospitalization time was 17.33 ± 5.87 days. Contacts who were not in close contact were infected. 

Conclusion: Patients are infectious in the incubation period, and asymptomatic patients are also infectious. The infectivity of the Shenzhen group was stronger than that of the Wuhan group. In the Shenzhen group, the time of positive-to-negative conversion of COVID-19 nucleic acid was longer, and the length of hospital stay was longer.