Objective: To analyze the characteristics of individuals positive for SARS-CoV-2 nucleic acid in a centralized isolation site for people entering China in Huzhou City of Zhejiang Province from December 18, 2021 to January 12, 2022, so as to provide insights into the prevention and control of overseas imported COVID-19. Methods: The basic characteristics, nucleic acid detection and epidemiological investigations were collected from individuals positive for SARS-CoV-2 nucleic acid in a centralized isolation site for people entering China from December 18, 2021 to January 12, 2022, and the temporal distribution, population distribution, source of importation, and virus typing were descriptively analyzed. Results : From December 18, 2021 to January 12, 2022, a total of 2 974 individuals in 19 flights were recorded in this centralized isolation site, and 33 cases were tested positive for SARS-CoV-2 nucleic acid, including 21 confirmed cases with common type, 9 confirmed cases with mild type, and 3 cases with asymptomatic infections. There were 11 cases with Omicron infections ( 33.33% ), 5 cases with Delta infections ( 15.15% ), and 17 cases with infection of unidentified types ( 51.52% ). The median interval ( interquartile range ) from the time of entry to the time of a positive test was 4.0 ( 7.0 ) days among all positive cases, 0 ( 4.0 ) day among cases with Omicron infections and 4.5 ( 8.5 ) days among cases with infections of Delta and unidentified types. The positive cases had a mean age of ( 36.97±8.58 ) years, and included 27 men (81.82%). There were 30 cases ( 90.91% ) receiving two and more doses of COVID-19 vaccines, and 7 cases ( 21.21% ) with a previous history of SARS-CoV-2 infections. There were 19 cases ( 57.58% ) from African countries, and 7 of 11 cases with Omicron infections were imported from African countries. Conclusion Omicron infection was predominant among individuals positive for SARS-CoV-2 nucleic acid in this centralized isolation site for people entering China from December 18, 2021 to January 12, 2022, with no severe cases detected, and most positive cases were imported from African countries.

Phthalic acid esters (PAEs) are commonly used plasticizers and solvents. Human body is exposed and absorbed mainly through diet, skin and air inhalation. The biological samples such as urine, blood, saliva, semen and breast milk generally contain PAEs and their metabolites, but the concentrations of PAEs metabolites vary in different samples. In the general population, the levels of PAEs are higher in children than in adults, and higher in women than in men; the levels of PAEs are higher in the occupational population than in the general population. In this paper, the research of PAEs related human biomonitoring in the general population and occupational population at home and abroad is reviewed, so as to provide the basis for reducing the exposure of PAEs and related health risk.