Influenza surveillance among children aged 0-14 years old in Chongqing City from 2017 to 2021
Objective To analyze the epidemiological characteristics of influenza among children aged 0-14 years old in Chongqing City from 2017 to 2021,and to provide scientific evidence for control and prevention of influenza in children.Methods The reported cases of influenza like illness(ILI)and etiological surveillance data among children aged 0-14 years old in Chongqing City from January 2017 to December 2021 were collected through the China Influenza Surveillance Information System.Descriptive epidemiological analysis was conducted to study the epidemiological characteristics of influenza among children.Results The proportion of ILI cases among children aged 0-14 years old was 1.48％in Chongqing City from 2017 to 2021.The positive rate of influenza virus nucleic acid was 13.51％.And the positive rates were 21.24％,12.67％,20.64％,1.91％and 10.75％from 2017 to 2021,respectively.There were significant differences in nucleic acid positive rate in different years(P＜0.05).The nucleic acid positive rate was the highest in the student group(25.02％),followed by children in nursery care group(18.55％)and scattered children group(7.09％).There were significant differences in the positive rate among the three groups(x2=1 150,P＜0.001).Influenza epidemic of children was mainly concentrated in winter and spring of each year.The months with high incidence of influenza in children were November to January of the next year,with the highest influenza positive rate.Influenza A was the dominant type in spring,and new H1N1 was the dominant strain.Influenza B was the dominant type in summer,autumn and winter,and the positive rate of Victoria lineage virus was higher.Age group analysis showed that the influenza like cases were mainly distributed in children aged 0-5 years old age group,but the positive rate of influenza was not high.Although there were fewer influenza like cases in children aged 7-14 years old age group,the positive detection rate of influenza virus nuclei acid was the highest.No statistically significant differences were found in the positive rate of influenza virus as well as in the proportion of different types of influenza virus between male and female children.Conclusions Influenza among children in Chongqing City was at a seasonal epidemic level from 2017 to 2021,and the positive rate was higher in winter and spring.The dominant strains of influenza in children weredifferent in different years and showed an alternating cycle.Preschool children and students,with high incidence of influenza,are the key groups of influenza prevention and control,and among whom influenza vaccination should be strengthened.
influenza virusinfluenza in childrenepidemiological characteristicssurveillance
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