ABSTRACT
Objective To analyze the distribution and epidemiological characteristics of influenza pathogens in Huai’an City from 2017-2019, and to provide a scientific basis for prevention and control of influenza. Methods The influenza-like illness (ILI) and outbreaks data was collected from China Influenza Surveillance Information System from 2017 to 2019. A descriptive analysis method was used to analyze the influenza data. Results A total of 103 082 ILI cases were reported in Huai’an City from 2017 to 2019, accounting for 8.96% of the total outpatient and emergency department visits. Winter and spring were the seasons for the high incidence of influenza, and children under 15 years old were the key population with high incidence. A total of 37 influenza outbreaks occurred in the city, with 774 reported cases. The epidemics mainly occurred in kindergartens, elementary schools, and junior high schools. There were 6,730 samples tested in the laboratory, 1,093 were positive for nucleic acid test, and the positive rate was 16.24%. Of the 1,093 positive samples, 417 were tested positive for H1N1 type, accounting for 38.15%; 251 were positive for seasonal H3 type, accounting for 22.96%; 274 were positive for Victoria subtype, accounting for 25.07%; and 151 were positive for Yamagata subtype, accounting for 13.82%. The types of dominant influenza strains alternated, and sometimes several types of influenza viruses coexisted. Conclusion Influenza often occurs in schools and has obvious seasonality. It is recommended that high-risk groups be vaccinated with quadrivalent influenza vaccine.
ABSTRACT
ObjectiveTo analyze the epidemiological characteristics and incidence trend of influenza-like illness in Xuhui District from 2010 to 2019， in order to understand the patterns of influenza epidemic of Xuhui District，and to provide evidence for the prevention and control of influenza in the future. MethodsSurveillance data of influenza-like illness （ILI） in Xuhui District from 2010 to 2019 were collected from the National Influenza Surveillance System for statistical description and trend analysis. ResultsFrom 2010 to 2019， the overall proportion of influenza-like illness was 0.54%. The annual proportions of ILI were between 0.35%~1.14%．The majority of cases were reported in age group of 25~59， accounted for 54.50% of the total ILI. A total of 9 053 throat swab specimens from ILI patients were collected and tested， from which 2 137 specimens were positive， with a positive rate of 23.61%. The most frequent subtype of influenza virus detected was influenza A virus （accounting for 67.62%）. The proportion of ILI and the positive rate of influenza virus nucleic acid detection reached the peak in summer and winter over time. There was a positive correlation between the proportion of ILI and the positive rate of influenza （r=0.666， P<0.01）. From 2010 to 2019， both ILI% and nucleic acid positive rate of influenza virus showed a downward trend. ConclusionThe incidence of influenza shows a downward trend in Xuhui District， with two peaks in summer and winter. The most susceptible individuals are in 25~59 age group. The dominant strains of influenza virus alternate regularly， influenza A（H3N2） dominate the summer epidemic peak while the epidemic peak in winter is dominated by influenza A（H1N1） and influenza B.
ABSTRACT
ObjectiveTo analyze the epidemiological characteristics and incidence trend of influenza-like illness in Xuhui District from 2010 to 2019， in order to understand the patterns of influenza epidemic of Xuhui District，and to provide evidence for the prevention and control of influenza in the future. MethodsSurveillance data of influenza-like illness （ILI） in Xuhui District from 2010 to 2019 were collected from the National Influenza Surveillance System for statistical description and trend analysis. ResultsFrom 2010 to 2019， the overall proportion of influenza-like illness was 0.54%. The annual proportions of ILI were between 0.35%~1.14%．The majority of cases were reported in age group of 25~59， accounted for 54.50% of the total ILI. A total of 9 053 throat swab specimens from ILI patients were collected and tested， from which 2 137 specimens were positive， with a positive rate of 23.61%. The most frequent subtype of influenza virus detected was influenza A virus （accounting for 67.62%）. The proportion of ILI and the positive rate of influenza virus nucleic acid detection reached the peak in summer and winter over time. There was a positive correlation between the proportion of ILI and the positive rate of influenza （r=0.666， P<0.01）. From 2010 to 2019， both ILI% and nucleic acid positive rate of influenza virus showed a downward trend. ConclusionThe incidence of influenza shows a downward trend in Xuhui District， with two peaks in summer and winter. The most susceptible individuals are in 25~59 age group. The dominant strains of influenza virus alternate regularly， influenza A（H3N2） dominate the summer epidemic peak while the epidemic peak in winter is dominated by influenza A（H1N1） and influenza B.