Cookie policy: This site uses cookies (small files stored on your computer) to simplify and improve your experience of this website. Cookies are small text files stored on the device you are using to access this website. For more information please take a look at our terms and conditions. Some parts of the site may not work properly if you choose not to accept cookies.

  • 2 of 4

Effectiveness of the different flu vaccines

The WHO coordinates a network called the Global Influenza Surveillance and Response System (GISRS), consisting of 142 National Influenza Centres (NICs) as well as various collaborating centres and laboratories. Recommendations for vaccine composition are made by the WHO in February for the following winter’s flu season in the Northern hemisphere. Antigenic drift of circulating viruses can occur in the interim, leading to a mismatch between the vaccine and circulating strains, and low vaccine effectiveness.