Surveillance & monitoring

The WHO’s Global Influenza Programme (GIP) provides global standards for influenza surveillance. In addition GIP collects and analyses virological and epidemiological influenza surveillance data from around the world. The regular sharing of quality influenza surveillance and monitoring data by countries allows WHO to:

  • provide countries, areas and territories with information about influenza transmission in other parts of the world to allow national policy makers to better prepare for upcoming seasons;
  • describe critical features of influenza epidemiology including risk groups, transmission characteristics, and impact;
  • monitor global trends in influenza transmission; and
  • support the selection of influenza strains for vaccine production.
    • The WHO’s Global Influenza Programme (GIP) provides global standards for influenza surveillance.
    WHO/Harold Ruiz
    © Credits

    Case definitions for influenza surveillance

    As of January 2014

    The WHO global influenza surveillance standards define the surveillance case definitions for influenza-like illness (ILI) and severe acute respiratory infections (SARI).

    Key messages when using the case definitions:

    • Influenza infection causes a clinical syndrome not easily distinguished from other respiratory infections.
    • The case definitions for ILI and SARI are not necessarily intended to capture all cases but to describe trends over time.
    • Using one common case definition globally will allow national health authorities to interpret their data in an international context.

     

    ILI case definition

    Acute respiratory infection with:

    • measured fever of ≥38 ⁰C
    • and cough;
    • with onset within the last 10 days.

    SARI case definition

    Acute respiratory infection with:

    • history of fever or measured fever of ≥38 ⁰C
    • and cough;
    • with onset within the last 10 days;
    • and requires hospitalization.
    Revision of clinical case definitions: influenza-like illness and severe acute respiratory infection, 2018

    Selected manuals and protocols

    Publications

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