南京市输入的新型冠状病毒感染病例的流行特征分析

Andysis of epidemiologic features of imported COVID-19 cases in Nanjing City

目的分析南京市2020年1月—2022年7月报告输入的新型冠状病毒感染病例的流行特征,为疫情防控提供参考依据。方法通过中国疾病预防控制信息系统、流行病学调查报告获取感染者资料,对相关数据进行描述流行病学分析。结果2020年1月1日—2022年7月31日,南京市共报告输入的新型冠状病毒感染病例360例,63.89%(230/360)为无症状感染者。男女性别比为2.40∶1,发病年龄以20~<40岁为主。58.06%(209/360)的COVID-19病例来自意大利、俄罗斯、新加坡和尼日利亚。入境—首次核酸采样阳性的时间间隔中位数(median,M)(P_(25),P_(75))为2(0,6)d,33.06%(119/360)的COVID-19病例在入境当日采样即核酸阳性。从新型冠状病毒疫苗接种情况看,48.61%(175/360)输入的新型冠状病毒感染病例接种过新型冠状病毒疫苗,不同年龄组的接种情况差异有统计学意义(χ^(2)=9.593,P=0.044)。是否接种过新型冠状病毒疫苗在Ct值上差异无统计学意义[ORF1ab基因(硕世试剂:Z=-0.223,P=0.824;达安试剂:Z=-0.150,P=0.880);N基因(硕世试剂:Z=-1.024,P=0.306;达安试剂:Z=-0.580,P=0.562)]。结论南京市输入的新型冠状病毒感染病例以无症状为主,中青年男性居多。作为报告南京市输入的新型冠状病毒感染病例最多的禄口机场,外防输入仍是其疫情防控工作的重点。

Objective To analyze the epidemiologic features of imported COVID-19 cases in Nanjing from January 2020 to July 2022,and provide reference basis for epidemic prevention and control.Methods Information on infected persons was obtained from the Information System of Chinese Disease Control and Prevention and epidemiology investigation reports,and relevant data were analyzed in a descriptive epidemiological manner.Results From 1 January 2020 to 31 July 2022,a total of 360 imported COVID-19 cases were reported in Nanjing,of which 63.89%(230/360)were asymptomatic.The sex ratio of male-to-female was 2.40∶1,and the median age of onset was predominantly 20 to<40 years.Fifty-eight point zero six percent(209/360)COVID-19 cases were from Italy,Russia,Singapore,and Nigeria.The time interval of median(M)(P_(25),P_(75))from the entry to the first positive nucleic acid sample was 2(0,6)days,and 33.06%(119/360)COVID-19 cases had the first positive nucleic acid detection on the day of the entry.In terms of the vaccination with the SARS-CoV-2 vaccine,48.61%(175/360)of the imported COVID-19 cases had received the COVID-19 vaccine,and there was a statistically significant difference(χ^(2)=9.593,P=0.044)in the vaccination status among different age groups.There was no statistically significant difference in Ct value between the vaccinated group and the unvaccinated group[ORF1ab gene(Bioperfectus reagent:Z=-0.223,P=0.824;DAAN reagent:Z=-0.150,P=0.880);N gene(Bioperfectus reagent:Z=-1.024,P=0.306;DAAN reagent:Z=-0.580,P=0.562)].Conclusion The imported COVID-19 cases in Nanjing are mainly asymptomatic,and most of them are young and middle-aged men.Lukou Airport as the site with the highest number of reported imported COVID-19 cases in Nanjing,and the prevention of imported cases is still the key to epidemic prevention and control.