Background Influenza viruses have emerged as virulent pathogens causing considerable burden across the world. A thorough understanding of the pattern in occurrence of influenza globally is the need of hour. The present study deals with analysis of the dynamics of Influenza virus, especially the influence of seasonal change on viral circulation and causation of epidemics/pandemics in the context of subtropical region. Methods During the 7 year (2009-2015) study, 36670 specimens were subjected to influenza analysis. Nasopharyngeal swabs collected from suspected patients from Chennai, Tamil Nadu, were tested and typed by real-time polymerase chain reaction assay. Results During 2009 pandemic, among influenza A positives 95.16% were Apdm09, indicating that there was a predominant circulation of Apdm09. During postpandemic period, there were waves in the occurrence of Apdm09 which indicates fall in immunity with buildup in the susceptible population. Conclusion In Chennai, Tamil Nadu, influenza positivity started with the onset of monsoon and peaks during the postmonsoon months throughout the study period. The assessment of meteorological factors compounding influenza activity can help in raising alerts to the public health officials of impending disaster which suggests that Influenza vaccination can be initiated before monsoon months in South India.

中文翻译：

---

泰米尔纳德邦钦奈与季节变化相关的流感发生动态：一项 7 年累积研究。

背景 流感病毒已作为剧毒病原体出现，给全世界带来了相当大的负担。彻底了解全球流感的发生模式需要一个小时。本研究主要分析流感病毒的动态，特别是季节性变化对亚热带地区病毒传播和流行病/大流行的原因的影响。方法在7年（2009-2015）的研究中，对36670份标本进行了流感分析。从泰米尔纳德邦钦奈的疑似患者身上采集的鼻咽拭子，通过实时聚合酶链反应分析进行了检测和分型。结果2009年流感大流行期间，甲型流感阳性者中Apdm09占95.16%，表明Apdm09占主导地位。疫情后期，Apdm09出现一波又一波，说明易感人群免疫力下降而增强。结论 在泰米尔纳德邦钦奈，流感阳性随着季风爆发而开始，并在整个研究期间的季风后几个月达到高峰。对加剧流感活动的气象因素的评估有助于向公共卫生官员发出即将发生的灾难的警报，这表明印度南部可以在季风月份之前开始接种流感疫苗。