Global Alert and Response (GAR)

WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases - Influenza

Description of the data

WHO has developed a web-based database called FluNet, ( on which data from centres in the influenza network are entered. The data consists of weekly reports of influenza activity in each location, categorized as no activity, sporadic, local, regional and widespread outbreaks. It also includes the numbers of influenza specimens isolated by type, subtype and prototype. There is a cumulative seasonal summary included in the database, providing a description of recent and current influenza activity around the world. The data are geographically referenced at the country level, and charts, maps and tables are available for view on the FluNet website, which has an average of over 4000 hits per day. The database dates from 1997, and it includes data from countries in all continents.

Strengths and weakness of the surveillance system

The WHO network of collaborating centres for influenza is a long-running surveillance system, that has provided important information on strains of influenza since its inception in 1947. The system ensures collection and immediate transport of influenza virus isolates to WHO Collaborating Centres together with epidemiological data for rapid virus characterization, which is the basis of the biannual updated recommendations for vaccine composition. The network has proven to be a reliable and successful system. However, it is important to increase worldwide coverage. There are many countries not included in the network, and other countries where there are too few centres to cover large geographic areas. Particular attention needs to be paid in those areas where animal hosts and humans live in close proximity, since those areas are considered to be the most likely places for new antigenic changes to take place.

Concerning dissemination of data on recent and current influenza activity, the web system has increased the access to information about current and recent influenza activity. In addition, information on current outbreaks of influenza is presented in the Weekly Epidemiological Record.