Abstract：Objective To analyze the epidemiological characteristics of overseas imported cases with coronavirus disease 2019 (COVID-19) in Zhejiang Province, so as to provide insights into containment of overseas imported COVID-19. Methods The pertaining to overseas imported COVID-19 cases in Zhejiang Province during the period between January 1, 2020 and May 31, 2022 were captured from the Chinese Disease Prevention and Control Information System. The temporal, spatial and population distributions, the duration from entry to the first time of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid test, and COVID-19 vaccination of overseas imported COVID-19 cases were analyzed using a descriptive epidemiological method. Results A total of 1 535 overseas imported COVID-19 cases were reported in Zhejiang Province during the period between January 1, 2020 and May 31, 2022, including 596 confirmed cases and 939 asymptomatic infections, and all reported cases were imported from 102 countries and territories. Overseas imported COVID-19 cases were reported in each month during the period between March 2020 and May 2022 except May 2020, and the mean monthly number of reported overseas imported COVID-19 cases was 125 during the period between December 2021 and May 2022. Overseas imported COVID-19 cases were reported across 11 cities of Zhejiang Province, with the largest numbers reported in Hangzhou (978 cases) and Jiaxing cities (177 cases), and imported cases were reported in 76.09% of counties (districts) in Zhejiang Province. The overseas imported COVID-19 cases were predominantly identified among individuals with Chinese nationality (88.79%), at ages of 20 to 39 years (59.09%), and students (21.82%), workers (17.20%) and business servants (17.00%) were predominant occupations among the overseas imported COVID-19 cases. The median duration from entry to the first time of positive SARS-CoV-2 nucleic acid test was 3.98 (7.06) d during the period between January 1, 2020 and May 31, 2022, and was 3.23 (4.97) d during the period between December 1, 2021 and May 31, 2022, which was significantly shorter than that during the period between January 1, 2020 and November 30, 2021 (P<0.001). The proportion of normal and more severe types of COVID-19 was 15.69% among cases without COVID-19 vaccination, which was significantly higher than that (7.77%) among those receiving booster vaccination (χ2=5.345, P=0.021), but was not significantly different from that (12.65%) among those receiving full-dose vaccination (χ2=0.971, P=0.324). Conclusions Students with Chinese nationality, workers and business servants were predominant among overseas imported COVID-19 cases in Zhejiang Province until May 31, 2022. The duration from entry after December 1, 2021 to identification of overseas imported COVID-19 cases shortened, and booster COVID-19 vaccination facilitated the alleviation of severity of clinical symptoms. There is a long-term risk of overseas importation of COVID-19 in Zhejiang Province, and the containment of imported COVID-19 requires to be sustainably implemented among entry personnel.
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