A cluster of COVID-19 caused by a presymptomatic case in Haikou / 预防医学

ABSTRACT

Objective@#To investigate a cluster of coronavirus disease 2019(COVID-19)caused by latent infection in Haikou,so as to provide reference for the prevention and control of COVID-19 clusters. @*Methods@#An epidemiological investigation was conducted according to the COVID-19 Prevention and Control Program(Fourth Edition). The course of diagnosis and treatment,clinical characteristics and field investigation data were collected to analyze the transmission chain and the intergeneration between cases. @*Results @#Among 39 people involved,five confirmed cases and two asymptomatic infections were found,with an attack rate of 17.95%. The cases aged from 40 to 65 years and lived in the dormitories near the farm of Dongshan. The first case(named Case 1)closely contacted with a confirmed case of COVID-19 in Chengmai from January 28 to February 10,was isolated on February 13 and developed symptoms on February 16. The other six cases(Case 2 to Case 7)shared the water source with Case 1 from January 28 to February 13(within the incubation period of Case 1). They needed to open the power switch outside Case 1's room and the water valve in Case 1's washroom before the use of water. They might be infected by contacting the doorknob and the water valve contacted by Case 1,or by the aerosol formed after Case 1 used the washroom,then infected each other when living together. The onset of Case 2 to Case 7 was earlier than Case 1,and they had no travelling history in Hubei Province 14 days before and contacted no confirmed cases except Case 1. Therefore,Case 1 was the source of the cluster during his incubation period of COVID-19. @*Conclusion@#This was a cluster of COVID-19 due to latent transmission by living in the same area and touching the same objects indirectly,which indicated that COVID-19 was infectious in the incubation period.