[Epidemiological characteristics of imported COVID-19 cases in Tianjin]

Objective: To understand the epidemiological characteristics of imported COVID-19 cases in Tianjin, and provide references for risk assessment and control of imported COVID-19 cases. Methods: The information of imported COVID-19 cases were obtained from National Notifiable Disease Report System of China CDC. The data of imported COVID-19 cases reported from Tianjin airport and epidemiological surveys by CDCs at all levels from March 15, 2020 to August 31, 2021 were collected and analyzed by using software Excel 2010, SPSS 25.0 and R. Results: From March 15, 2020 to August 31, 2021, a total of 606 imported cases of COVID-19 were reported in Tianjin, in which 552 cases were finally included in the analysis. The male to female ratio of the cases was 1.8∶1, the age of the cases ranged from 3 to 77 years, and the cases were mainly reported in age group 20-39 years (59.8%). The areas where the imported case sojourned within 14 days included Europe (242 cases, 43.8%), Africa (139 cases, 25.2%), Americas (85 cases, 15.4%) and Asia (86 cases, 15.6%). The proportion of confirmed cases in autumn and winter was relatively high. During the study period, the proportion of infected persons found in custom entry quarantine decreased, and the proportion of persons with personal health declaration and under medical isolation observation increased. The interval between entry and diagnosis of infected persons tended to increase. Conclusion: The proportion of imported COVID-19 cases detected on the first day of entry at Tianjin airport decreased, and the interval to detect the infected persons trended to increase, to which close attention must be paid.