Epidemiological and Virological Characteristics of Influenza in Chongqing, China, 2011-2015.

Li Qi,Wenge Tang,Sheng Ye,Bangzhong Xiao,Yu Xiong,Hua Ling,Han Zhao,Jiang Long,Zhen Yu,Qin Li,Shuang Chen,Dayong Xiao,Cristina Costa

doi:10.1371/journal.pone.0167866

Abstract

BackgroundChongqing is the largest municipality and located in Southwestern of China, with over 30 million registered inhabitants. There are few reports regarding the epidemiology of influenza in Chongqing. The objective of the paper is to explore the epidemiology of influenza in Chongqing, in order to provide scientific basis for prevention and control of influenza.Methodology /Principal FindingsFrom 2011 to 2015, we collected information on influenza-like illness (ILI) patients fulfilling the case definition, and took nasalpharyngeal or throat swabs specimens from ILI cases per week at the 7 sentinel hospitals. Specimens were tested by reverse transcription-polymerase chain reaction(RT-PCR) for influenza. Descriptive epidemiology was applied to analyze the epidemiology and etiology of influenza. A total of 9,696,212 cases were enrolled, of which 111,589 were ILI. Of those 24,868 samples from ILI cases, 13.3% (3,314/24,868) tested positive for influenza virus (65.7% influenza A, 34.1% influenza B, and 0.2% influenza A and B co-infection). Among the influenza A viruses, 71.3% were seasonal influenza A(H3N2) and 28.7% were influenza A(H1N1)pdm09. No cases of seasonal A(H1N1) were detected. The isolation rate was highest in children aged 5–14 years old. Influenza activity consistently peaked during January-March in 2011–2015, and June-July in 2012, 2014 and 2015.ConclusionsInfluenza is an important public health problem among ILI patients in Chongqing, especially among school-aged children. It might be beneficial to prioritize influenza vaccination for school-aged children and implement the school-based intervention to prevent and mitigating influenza outbreaks in Chongqing, particularly during the seasonal peaks.

Highlights

Influenza is a common vaccine-preventable disease and a major cause of mortality and morbidity globally
According to World Health Organization (WHO), it is estimated that about 5%– 10% of adults and 20%– 30% of children globally are affected by influenza annually, resulting in about 3 to 5 million cases of severe illness, and about 250000 to 500000 deaths [1]
We summarize the findings of expanded influenza surveillance in Chongqing during 2011–2015, when the surveillance was fully implemented, and provide a scientific basis for prevention and control of influenza

Summary

Introduction

Influenza is a common vaccine-preventable disease and a major cause of mortality and morbidity globally. Chongqing is the largest municipality, with over 30 million registered inhabitants, and is located in the subtropical region at latitude 29.6 ̊N in Southwestern of China. Influenza surveillance was initiated in 2005 in Chongqing, including 4 sentinel hospitals. There are few reports regarding the epidemiology of influenza in Chongqing, which in turn hampered identifying the optimal region-specific policy to diminish disease burden. To better understand the epidemiological and virologic characteristics of influenza in Chongqing, the surveillance was extended to 3 additional sentinel hospitals since 2011. Chongqing is the largest municipality and located in Southwestern of China, with over 30 million registered inhabitants. There are few reports regarding the epidemiology of influenza in Chongqing. The objective of the paper is to explore the epidemiology of influenza in Chongqing, in order to provide scientific basis for prevention and control of influenza

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Conclusion