2016-2022年杭州流感病毒流行特征及儿童流感重症感染特征分析

Epidemic characteristics of influenza virus and features of severe influenza infection in children in Hangzhou from 2016 to 2022

目的了解儿童流感流行特征及流感重症的感染特征。方法收集2016年1月—2022年9月严重急性呼吸道感染住院病例样本1600份,门诊流感样病例监测样本7660份。实时荧光PCR法检测流感病毒。并对流感住院重症病例样本及部分流感门诊病例样本进行其他呼吸道病毒的检测,分析其临床感染特征和合并感染特征。结果1600份严重急性呼吸道感染住院病例样本中,流感病毒阳性率为6.63%(106例),甲型H1N1、H3N2、B Victoria(BV)、B Yanagata(BY)的占比分别为49.06%(52/106)、17.92%(19/106)、29.25%(31/106)和3.77%(4/106)。7660份门诊病例中,流感阳性率为15.01%(1150例),甲型H1N1、H3N2、BV、BY的占比分别为22.17%(255/1150)、30.96%(356/1150)、41.39%(476/1150)和5.48%(63/1150)。甲型H1N1流感病毒更容易引起儿童流感重症,差异具有统计学意义(χ^(2)=37.978,P<0.001),而季节性H3N2和BV流感病毒不容易引起幼儿流感重症(χ^(2)=7.871,P=0.005;χ^(2)=5.948,P=0.015)。BY流感病毒在两种病例中的占比差异无统计学意义。流感重症主要发生在流感流行高峰季节。4种流感病毒引起儿童的临床感染特征无明显差异。106例流感重症中,其他呼吸道病毒的合并感染率为17.92%(19例),135例流感门诊病例中,其他呼吸道病毒合并感染率为34.81%(47/135),门诊病例合并感染率更高,且差异具有统计学意义(χ^(2)=10.734,P=0.001)。结论甲型H1N1流感病毒更容易引起儿童流感重症,季节性H3N2和BV型不易引起儿童流感重症。4种流感病毒引起的儿童临床感染特征无明显差异。其他呼吸道病毒的合并感染不是引发儿童流感重症的主要危险因素。

ObjectiveTo investigate the epidemic characteristics of influenza in children and the features of severe influenza.MethodsFrom January 2016 to September 2022,1600 samples from hospitalized cases of severe acute respiratory tract infection and 7660 samples from outpatients with influenza-like illness were collected.Influenza virus was detected by real-time RT-PCR.Other respiratory viruses in the samples of severe hospitalized cases and some samples of outpatients were detected.Clinical features of influenza virus infection and co-infection were analyzed.ResultsThe positive rate of influenza virus in the 1600 hospitalized cases of severe acute respiratory infection was 6.63%(106 cases).H1N1,H3N2,BV and BY were deteted in 49.06%(52 cases),17.92%(19 cases),29.25%(31 cases)and 3.77%(4 cases)of the 106 cases,respectively.The positive rate of influenza virus in the 7660 out-patient cases was 15.01%(1150 cases),and H1N1,H3N2,BV and BY were detected in 22.17%(255 cases),30.96%(356 cases),41.39%(476 cases)and 5.48%(63 cases)of the infected cases,respectively.Influenza A(H1N1)virus was more likely to cause severe influenza in children(χ^(2)=37.978,P<0.001),while seasonal H3N2 and BV strains were less likely to cause severe influenza in children(χ^(2)=7.871,P=0.005;χ^(2)=5.948,P=0.015).There was no statistically significant difference in the positive rates of BY lineage in the two groups.Severe influenza mainly occured in the peak season of influenza epidemic.There was no significant difference in the clinical manifestations between the children infected with the four different influenza viruses.In the 106 severe cases of influenza,the co-infection rate of influenza virus with other respiratory viruses was 17.92%(19 cases),while the co-infection rate reached 34.81%(47 cases)in 135 outpatient cases of influenza.The difference in the co-infection rates was statistically significant between outpatient and hospitalized cases(χ^(2)=10.734,P=0.001).ConclusionsInfluenza A(H1N1)virus was more likely to cause severe influenza in infants and young children in comparison with seasonal H3N2 and BV.There was no significant difference in the clinical features of influenza caused by H1N1,H3N2,BV and BY.Co-infection of influenza virus with other respiratory viruses is not a major risk factor for severe influenza in infants.