Epidemiological investigation on a cluster epidemic of COVID-19 in Taizhou， Zhejiang Province / 上海预防医学

ABSTRACT

Objective:To analyze the epidemiological characteristics of a family and workplace clustering of COVID-19， identify the source of infection and the transmission chain， and provide evidence for prevention and control of COVID-19 pandemic. Method:Field epidemiological method was used to conduct the investigation of confirmed cases and close contacts in this cluster. Data were analyzed with descriptive method. Real-time fluorescent quantitative PCR （RT-PCR） was used to detect the novel coronavirus nucleic acid in the collected respiratory tract samples. Results:A total of 18 epidemiological related cases were collected including 16 confirmed cases and 2 cases of asymptomatic infections. The involved places included 1 beauty clinic workplace and 3 families. Seven cases were males and 11 cases were females， with the minimum， maximum and median age of 3， 65 and 32 years old， respectively. Among them， the employees attack rate was 9.80% （10/102）， the family attack rate was 7.70% （5/78）， and the customer attack rate was 0.58% （1/173）. Positive nucleic acid test result in the respiratory tract sample of asymptomatic infection lasted for more than 2 months. Conclusions:The cause of this clustered COVID-19 epidemic is that the workplace environment is relatively closed with clustering crowds， and the source of imported infection is not discovered in time， which lead to a point-source outbreak and spread through family close contacts and clustering.