Analysis of influenza epidemic surveillance in Huai’an City in 2017-2019 / 公共卫生与预防医学

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.