Dorji Tshering, Dorji Kunzang, Chettri Vishal, Gyeltshen Sonam, Sadler Holly
National Influenza Centre (NIC), Royal Centre for Disease Control, Thimphu, Bhutan.
Food and Nutrition Laboratory (FNL), Royal Centre for Disease Control, Thimphu, Bhutan.
Influenza Other Respir Viruses. 2025 Mar;19(3):e70095. doi: 10.1111/irv.70095.
Influenza presents a significant global health challenge, with seasonal epidemics causing 3 to 5 million cases of severe illness and 290,000 to 650,000 respiratory deaths annually. In Bhutan, the highest rates of influenza-associated hospitalizations were observed among children under 5 years of age emphasizing the need for robust surveillance and preparedness.
This study aims to assess influenza severity in Bhutan using the World Health Organization's (WHO) Pandemic Influenza Severity Assessment (PISA) framework. By integrating syndromic and influenza-specific data, we establish national-level baseline and threshold values for influenza activity.
The WHO Average Curve Method was employed to establish seasonal and intensity thresholds, categorizing influenza severity based on historical data from 2016 to 2019 and 2023.
Analysis of influenza activity revealed near-continuous activity with two annual peaks. Thresholds for epidemic, moderate, high, and extraordinary levels of transmissibility and morbidity were determined. The 2019 season exhibited the highest transmissibility and morbidity, with significant variability in intensity across different seasons.
The study demonstrates the effectiveness of the PISA framework in assessing influenza severity in Bhutan. The established thresholds provide a valuable tool for public health decision-making, enhancing the country's preparedness for both seasonal and pandemic influenza. These findings underscore the importance of maintaining and adapting surveillance systems to monitor influenza activity year-round.
流感是一项重大的全球健康挑战，季节性流行每年导致300万至500万例严重疾病病例以及29万至65万例呼吸道疾病死亡。在不丹，5岁以下儿童的流感相关住院率最高，这凸显了加强监测和防范的必要性。
本研究旨在使用世界卫生组织（WHO）的大流行性流感严重程度评估（PISA）框架评估不丹的流感严重程度。通过整合症状和流感特异性数据，我们建立了国家层面的流感活动基线和阈值。
采用WHO平均曲线法确定季节性和强度阈值，根据2016年至2019年以及2023年的历史数据对流感严重程度进行分类。
对流感活动的分析显示，流感活动几乎持续存在，每年有两个高峰。确定了流行、中度、高度和极高传播性及发病率水平的阈值。2019年季节的传播性和发病率最高，不同季节的强度存在显著差异。
该研究证明了PISA框架在评估不丹流感严重程度方面的有效性。所确定的阈值为公共卫生决策提供了有价值的工具，增强了该国对季节性流感和大流行性流感的防范能力。这些发现强调了维持和调整监测系统以全年监测流感活动的重要性。
