Analysis of influenza surveillance results in the sentinel hospitals of Anyang city,Henan province from 2012 to 2022
Objective To analyze the epidemic characteristics of influenza in Anyang city from 2012 to 2022,and provide scientific evidence for the prevention and control of influenza in this city.Methods The surveillance data of influenza-like cases(ILI)in sentinel hospitals were collected through China Influenza Surveillance Information System,and the pharyngeal swab samples of ILI collected in sentinel hospitals were detected by real-time PCR,and the surveillance results were described and analyzed.Results A total of 25 706 cases of ILI were reported in Anyang from 2012 to 2022,and of the outpatient volume,the total ILI cases accounted for 0.99％.A total of 6 569 ILI samples were detected,and 964 cases were positive for influenza virus nucleic acid,with a positive rate of 14.67％,of which 30.08％were influenza A(H3N2),25.52％were novel influenza A(H1N1),43.98％were influenza B,and 0.41％were mixed.During the ten surveillance years,only type B was detected in 2020/2021 and 2021/2022 seasons,and all types were detected during the other seven monitoring years(4 and 172 cases,respectively).A total of 694 influenza strains were isolated during the ten years,including 581 MDCK cell strains and 113 chicken embryo strains.The positive rate was the highest in the age group of 5-＜15years(21.12％),and the differences of nucleic acid positive rates in different surveillance years,months,age groups and sexes were statistically significant(P＜0.05).Conclusions From 2012-2022,the influenza epidemic in Anyang city was at a low level,stable,with no obvious trend of high incidence and with a peak in winter and spring.In the epidemic season,A-type H3N2,B-type and novel A-type H1N1 alternately became the dominant strains;children were the key groups for influenza prevention and control.
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