Baseline data is needed at programme outset so countries understand their burden of disease and subsequently can estimate the potential impact of the programme.
WHO’s publication Global epidemiological surveillance standards for influenza provides information on case definitions and epidemic thresholds developed by WHO’s Global Influenza Programme. WHO also offers summaries of global surveillance based on data gathered through global and regional data-sharing platforms and direct reports from Member States.
For practical use, the WHO manual on Estimating disease burden associated with seasonal influenza provides tools and methods to estimate disease burden on the basis of available surveillance data.
Further guidance and tools to set up, monitor, report on and analyse disease surveillance at district and national levels are offered in WHO’s Training for mid-level managers series, Module 8.
Where resources permit, establishment of sentinel sites should be considered for collecting virus samples and to assess vaccine impact by comparing vaccine coverage in laboratory-confirmed versus test-negative cases. Collaborating with WHO surveillance and epidemiology networks such as the SARI Sentinel Surveillance Network (SARINet) or the African Network for Influenza Surveillance and Epidemiology (ANISE) can support countries by allowing data analysis based on sufficient sample sizes from their member countries.