Influenza is an acute respiratory infectious disease caused by influenza virus. It usually exhibits seasonal transmission, but the novel influenza strain can lead to a pandemic with severe human health and socioeconomic consequences. Early warning of influenza epidemic is an important strategy and means for influenza prevention and control. On the basis of reviewing the main influenza surveillance and early warning systems, this study summarizes the principles, applications, advantages and disadvantages, and development prospects of common influenza early warning models, in order to provide reference for research and application of early warning technology for influenza and other acute respiratory infectious diseases.
Humans ; Influenza, Human/epidemiology* ; Pandemics/prevention & control*

Humans ; Influenza A virus ; Influenza Vaccines ; Influenza, Human ; epidemiology ; prevention & control ; virology

Disease Outbreaks ; Humans ; Influenza, Human ; epidemiology ; prevention & control

China ; epidemiology ; Humans ; Influenza Vaccines ; Influenza, Human ; epidemiology ; prevention & control ; therapy

Cardiovascular risk and related medical burden due to influenza in patients with chronic disease were higher than those of healthy subjects. As a result, influenza vaccination is recommended as a strategy for secondary prevention in cardiovascular disease by major cardiovascular organizations, but the prevalence of influenza vaccination in these population is still low. Whether influenza vaccine can prevent cardiovascular events such as myocardial infarction and death is still controversial based on current evidences from observational studies and case-control studies, which may result from study desion,subjects selection,outcome definition and sample size issues. Recent meta-analysis showed that influenza vaccination may reduce cardiovascular risk, but large-scale random controlled trials with adequately power should be conducted to confirm these findings as well as the target population for this strategy further.
Cardiovascular Diseases ; epidemiology ; prevention & control ; Humans ; Influenza Vaccines ; therapeutic use ; Influenza, Human ; epidemiology ; prevention & control ; Risk Factors ; Secondary Prevention ; Vaccination

Animals ; Birds ; virology ; China ; epidemiology ; Humans ; Influenza A virus ; classification ; pathogenicity ; Influenza Vaccines ; Influenza in Birds ; epidemiology ; prevention & control ; Influenza, Human ; epidemiology ; prevention & control

China ; epidemiology ; Epidemics ; prevention & control ; Humans ; Influenza, Human ; epidemiology ; prevention & control

China ; epidemiology ; Disaster Planning ; organization & administration ; Disease Outbreaks ; prevention & control ; Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; prevention & control

Animals ; Birds ; China ; epidemiology ; Humans ; Influenza A Virus, H5N1 Subtype ; physiology ; Influenza A Virus, H7N7 Subtype ; physiology ; Influenza A Virus, H9N2 Subtype ; physiology ; Influenza A virus ; physiology ; Influenza, Human ; epidemiology ; prevention & control

Objective: To analyze the epidemiological characteristics, etiology and hemagglutinin (HA) gene characteristics of prevalent strains in Shandong Province from 2021 to 2022. Methods: The sentinel surveillance data of influenza-like illness (ILI) were collected in Shandong Province from 2021 to 2022. ILI specimens were detected with Real-Time PCR and virus isolation to explore the distribution of influenza viruses in different months. Three virus strains of each city were selected for gene sequencing, and the HA phylogenetic analysis was carried out. Results: In the surveillance-year from 2021 to 2022, 528 263 ILI cases were totally reported in 54 sentinel hospitals for influenza surveillance in Shandong Province. ILI visiting ratio (ILI%) was 4.07%, with the largest number in 0-4 age group (45.86%). The highly frequent season for ILI was in winter and spring, with a peak in the 52nd week, 2021 (6.62%). Totally, nucleic acid was detected in 26 754 specimens, with a positive rate of 27.10%, all of which were type B Victoria influenza. The positive rate reached a peak in the 49th week, 2021 (63.78%). A total of 295 outbreaks of ILI had been reported, in which 269 were positive for influenza virus. Most of outbreaks occurred in the primary school, with a peak in December. Gene evolution analysis showed that the HA gene in Shandong possessed high homology, 98.6% to 99.5%, with the recommended vaccine strains in 2020-2023, which was divided into two branches, V1A.3a.1 and V1A.3a.2. Conclusion: In the surveillance-year of 2021-2022, influenza is prevalent in December in Shandong Province, with a single circulating strain type. The positive rate of influenza virus and outbreak are higher than those in the previous surveillance-year. The circulating strain possesses high HA gene homology with those of the WHO vaccine recommended strains. However, the overall immune barrier of influenza virus is weak.
Humans ; Influenza, Human/prevention & control* ; Phylogeny ; Influenza Vaccines ; Orthomyxoviridae ; Seasons ; China/epidemiology* ; Virus Diseases