Assessment of Influenza Severity in Bhutan by using WHO framework
Pandemic Influenza Severity Assessment (PISA): an Implementation
Research Study
Abstract
Background: 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. Objective: 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. Methods: The WHO Average Curve Method was employed to
establish seasonal and intensity thresholds, categorizing influenza
severity based on historical data from 2016-2019 and 2023.
Results: 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. Conclusion: 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.