3rd WHO Informal Consultation for Improving Influenza Vaccine Virus Selection

1 to 3 April 2014, Geneva, Switzerland


The constantly evolving nature of influenza viruses requires continuous global monitoring and frequent reformulation of influenza vaccines. Since 1952, the WHO Global Influenza Surveillance and Response System (GISRS) has been monitoring the emergence of new epidemic and pandemic viruses and has undertaken risk assessment of and response to emergence of influenza viruses with pandemic potential. Since 1973, formal recommendations for viruses to be included in influenza vaccines have been issued by WHO based data compiled through GISRS surveillance. Since 1998, such recommendations have been issued twice per year, in February and September for influenza seasons in the Northern and Southern Hemisphere influenza seasons respectively.

Vaccine virus selection involves coordinated collection and analysis of thousands of virus specimens globally, with the goal of selecting and recommending the vaccine viruses that will best protect against disease during the next influenza season. Due to the current vaccine technology and the time needed to produce influenza vaccines, vaccine virus selection has to take place almost a year in advance of the peak of influenza activity in the season when the vaccine will be used. Data used as a scientific basis for selecting vaccine viruses include information from hemagglutination inhibition assays and micro-neutralization tests using post-infection ferret sera as well as pre- and post-vaccination human sera combined with extensive sequence data, epidemiological and clinical information form the scientific bases for vaccine virus selection.

Similar data have been used for the selection of viruses for pandemic A(H1N1)2009 vaccines and for the selection of influenza A(H5), A(H7) including A(H7N9) and A(H9) viruses for pandemic preparedness purposes.

Significant improvements to influenza vaccine virus selection have been made over the years through concerted efforts to strengthen the WHO GISRS by 1) increasing the number, quality, timeliness and geographical distribution of influenza virus isolates analyzed by National Influenza Centers and WHO Collaborating Centers (CCs); 2) improving and standardizing laboratory assays; and 3) adopting new methods to enhance the vaccine virus selection. However, limitations remain with respect to the amount and timeliness of data available at the time decisions must be made, the laboratory technology used to characterize viruses and the methods used to analyze the data.

With growing awareness of influenza as an important global disease, increasing demand for influenza vaccines, development of new laboratory tests, and emerging new and high throughput technologies, WHO has held two informal consultations in Geneva 2010 and 2011 . The aim of these consultations was to explore ways to improve the process of vaccine virus selection by providing a platform for exploration and potential application of new approaches and technologies. In the two years since the 2nd WHO consultation, new knowledge has accumulated and technology has been developed. In addition, the need for increasing vaccine uptake by certain population groups has been recognized, e.g., maternal immunization with influenza vaccines, a program possibly supported by GAVI and Bill & Melinda Gates Foundation. All these developments present the need to hold a 3rd WHO consultation in order to further equip better the WHO vaccine virus selection process and to address emerging needs of public health significance.

Scope and objectives

The meeting aims to improve the influenza vaccine virus selection process through exploring ways to improve the extent, timeliness and quality of virological, epidemiological, and clinical surveillance data; the development and application of new assays and new modeling approaches; the understanding of the relationship between virus characteristics and vaccine efficacy; the understanding of needs in tropical areas for vaccine composition recommendations; and the general understanding of regulatory considerations.

The consultation will bring together influenza experts from around the world to review and discuss:

  • Surveillance issues related to increasing the number and timeliness of representative influenza viruses available for vaccine virus selection and the development of candidate vaccine viruses;
  • Epidemiological patterns and virological aspects in terms of optimal influenza vaccine composition for use in tropical areas;
  • Development of new assays and their potential use for influenza vaccine virus selection;
  • Development of tools including modeling for their potential use for influenza vaccine virus selection. This includes the correlation of antigenicity of viruses with genetic properties and vaccine efficacy as well as potential predictive modeling approaches;
  • Vaccine regulatory implications for the introduction of new technologies, materials and products relevant to vaccine virus selection and;
  • Next steps on this subject.

Participants (by invitation)

Experts from:

  • WHO Collaborating Centres for Influenza of GISRS
  • National Influenza Centres
  • WHO Essential Regulatory Laboratories
  • National epidemiological institutions
  • National Regulatory Authorities
  • Research and academic laboratories, institutions and organizations
  • Veterinary institutions and organizations
  • Human influenza vaccine manufacturers
  • Donor agencies and other stakeholders


  • Recapitulation of last meeting in December 2011
  • Improving influenza surveillance and availability of appropriate virus isolates
  • Optimal vaccine composition for tropical areas
  • Development and implementation of new assays
  • Correlation of antigenicity and efficacy of vaccines
  • New tools including modeling and additional data they generated
  • Needs from new vaccine development
  • Way forward

If you wish to participate in this meeting at your own cost, please send an e-mail to by Monday, 10 March 2014 to express your interest and to provide your full contact details. WHO will review the requests received and issue official invitation letters as appropriate. No registration fee is required.