Investigation of an epidemic cluster caused by COVID⁃19 cases in incubation period in Shanghai/ 上海市一起潜伏期病例传播的新型冠状病毒肺炎聚集性疫情调查

Objective To analyze the epidemiological characteristics of a cluster of 5 confirmed COVID⁃19 cases related with the transmission in incubation period of initial case, and find out the infection source and transmission chain Methods According to "The Prevention and Control Protocol for Coronavirus Disease 2019 (Third Edition)" issued by the National Health Commission, a field epidemiological survey was conducted for the 5 cases in January 2020 Nasopharyngeal swabs and sputum samples were collected from them for the detection of 2019-nCoV by real time RT-PCR Multi prevention and control measures were taken, such as tracking and screening close contacts, medical isolation observation, investigating the epidemiological link, analyzing transmission chain Results Case 1, who had common environmental exposure with other COVID⁃19 cases, got sick on 20 January, 2020 and was confirmed on 1 February Case 2 became symptomatic on 22 January and was confirmed on 27 January Case 3 got sick on 25 January and was confirmed on 30 January Case 4 had illness onset on 20 January and was confirmed on 1 February Case 5 got sick on 23 January and was confirmed on 31 January Among the 5 cases, case 2 died and the illness of other cases were effectively controlled After exclusion of other common exposure factors, case 1 had a 6-hour meeting with case 2 and case 3 on 19 January Case 2 and case 3 might be infected by case 1 during the incubation period It is the key point for epidemiological investigation Conclusion The epidemiological investigation indicates that the transmission might occur in the incubation period of COVID-19 case, close attention should be paid to it in future COVID-19 prevention and control