WHO Supports Sri Lanka: Influenza Burden Assessment Plan
- Seasonal influenza is a major public health challenge worldwide, causing an estimated one billion infections annually.
- Effective public health interventions, such as seasonal influenza vaccination, can mitigate these impacts.
- Accurately estimating the burden of influenza is notably challenging in low- and middle-income countries, where robust surveillance and data systems are frequently enough lacking.
Sri Lanka Moves Towards quantifying the Impact of Influenza
Table of Contents
Published August 21, 2025
The Global Burden of Influenza
Seasonal influenza is a major public health challenge worldwide, causing an estimated one billion infections annually. Of these, 3 to 5 million cases result in severe illness, disproportionately affecting vulnerable populations – older adults, young children under five, pregnant individuals, and those wiht underlying chronic conditions. Beyond the direct health consequences, influenza epidemics place a significant strain on economies and healthcare systems.
Effective public health interventions, such as seasonal influenza vaccination, can mitigate these impacts. However, informed decision-making requires a clear understanding of the true burden of disease within specific regions.
A Data Gap in Low- and Middle-Income Countries
Accurately estimating the burden of influenza is notably challenging in low- and middle-income countries, where robust surveillance and data systems are frequently enough lacking. This data scarcity hinders the progress and implementation of targeted public health strategies. Sri Lanka,a nation with a strong track record in controlling vaccine-preventable diseases,recognizes this need and is proactively addressing it.
Feasibility Assessment Initiated
In a significant step towards strengthening influenza preparedness, Sri Lanka has launched a feasibility assessment to determine the best approach for estimating the influenza Burden of Disease (BoD). This initiative is being supported by the Pandemic Influenza Preparedness (PIP) Partnership Contribution (PC) fund.
Evaluating Surveillance Systems
At the request of the Sri Lankan Ministry of Health, the World Health Institution (WHO) conducted an in-country mission from April 28 to May 9, 2025. The mission’s primary goal was to evaluate the existing influenza surveillance systems, specifically those monitoring severe acute respiratory infection (SARI) and influenza-like illness (ILI), and their capacity to generate reliable data for BoD estimation.
The assessment involved a thorough review of key documents, including standard operating procedures (sops) for influenza surveillance, data entry forms for the FluSys system, and publicly available information. A preliminary analysis of surveillance data submitted to WHO’s FluID and FluNet platforms was also conducted.
Key Informant Interviews and Stakeholder Engagement
The WHO team conducted key informant interviews (KIIs) with officials from the Ministry of Health’s Epidemiology Unit, the Medical Research Institute (MRI), the National Institute for Infectious Diseases (NIID), Lady Ridgeway Hospital (LRH), and staff from national public health and university laboratories. These interviews provided valuable insights into the current state of influenza surveillance and data collection in Sri Lanka. A debriefing meeting with the Chief Epidemiologist and stakeholders from the Epidemiology Unit and MRI followed, to discuss preliminary findings and outline a plan for BoD estimation.
Key Considerations for Implementation
Several key considerations have been identified for the full implementation phase of bod estimation in Sri Lanka:
- Ensuring consistent and complete patient-level data entry across all surveillance sites and laboratories, including demographic information, clinical indicators, and laboratory results.
- Identifying and prioritizing sentinel surveillance sites that provide high-quality data and represent clearly defined populations.
- implementing a standardized national protocol for the selection of ILI and SARI patients for virological testing to minimize bias.
- Standardizing ICD-10 coding practices to accurately identify SARI-related hospitalizations and catchment populations.
Next Steps and Regional impact
With strengthened virological surveillance and full utilization of existing infrastructure,Sri Lanka aims to generate reliable estimates of the influenza burden of disease. These estimates will be crucial in informing decisions regarding the potential introduction of seasonal influenza vaccination for high-risk groups.
This initiative aligns with the Global Influenza Strategy (2019-2030) and will serve as a model for other countries in the South-East Asia region. WHO’s Regional Office for South-East Asia plans to support additional countries in conducting similar feasibility assessments,ultimately leading to a better understanding of the health and socio-economic impact of influenza and strengthening global health security.