青海省西宁地区2016—2021年儿童流感流行特征及季节性分析

Epidemiological characteristics and seasonal analysis of influenza in children in Xining Region,Qinghai Province from 2016 to 2021

目的分析2016—2021年青海省西宁地区儿童流行性感冒(简称“流感”)病毒变迁规律,为高原地区流感防控提供科学依据。方法从“中国流感监测信息系统”导出流感样病例核酸和病毒分离数据。采用集中度和描述性流行病学方法,分析2016—2021年西宁地区14岁以下儿童流感特征。结果采集14岁以下儿童ILI鼻咽拭子标本11493例,占58.00%(11493/19814)。核酸阳性检出率为14.16%,病毒阳性分离率为25.45%,其中核酸阳性检出率2018—2019年为20.72%、以H1N1(pdm09)和B型/Victoria系为主;2017—2018年为19.03%,以4种病毒混合感染为主;2019—2020年为13.99%、以甲型H3N2为主,不同年份流感病毒优势毒株差异有统计学意义(χ^(2)=349.33,P<0.001)。流感发病高峰主要在12月中旬,占34.44%。核酸阳性检出率居前3的为12~<14岁(27.57%)、6~<9岁(20.69%)和9~<12岁(19.88%),随年龄增加检出率显著上升(χ_(趋势)^(2)=225.24,P<0.01)。2016—2021年流感发病集中度M值分别为0.86、0.84、0.93、0.96和0.86,M_(总计)=0.83。结论西宁地区儿童流感呈现每隔2年为甲型H3N2绝对优势株流行年,伴连续2年混合株流行年,儿童易患甲型流感,需注意乙型流感局部暴发。

Objective To analyze the changes law of Influenza virus in children in Xining Region,Qinghai Province from 2016 to 2021,so as to provide scientific basis for the prevention and control of influenza in plateau areas.Methods The nucleic acid and virus isolation data of influenza-like cases were derived from"China Influenza Surveillance Information System".Concentration degree and descriptive epidemiological methods were used to analyze the characteristics of influenza in children under 14 years old in Xining Region from 2016 to 2021.Results A total of 11493 ILI nasopharyngeal swabs from children under 14 years old were collected,accounting for 58.00%(11493/19814).The positive nucleic acid detection rate was 14.16%,and the positive virus isolation rate was 25.45%.The positive detection rate of nucleic acid in 2018-2019 was 20.72%,mainly H1N1(pdm09)and B/Victoria lineage.In 2017-2018,it was 19.03%,mainly mixed infection of four viruses.In 2019-2020,it was 13.99%,mainly A/H3N2.The difference of nucleic acid positive detection rate of the dominant strains of Influenza virus in different years was statistically significant(χ^(2)=349.33,P<0.001).The peak of influenza incidence was mainly in mid-December,accounting for 34.44%.The top three nucleic acid positive rates occurred among children of 12-<14 years old(27.57%),6-<9 years old(20.69%)and 9-<12 years old(19.88%),and the detection rate increased significantly with age(χ^(2)_(trend)=225.24,P<0.01).The median values of influenza incidence concentration from 2016 to 2021 were 0.86,0.84,0.93,0.96 and 0.86,respectively,and the total M value was 0.83.Conclusion The absolute dominant influenza A/H3N2 strains are prevalent in children in Xining Region every other two years,accompanied by two consecutive years of mixed strains.Children are prone to influenza A,and attention should be paid to the local outbreaks of influenza B.