Considerations for use of avian influenza A(H5) vaccines during the interpandemic and emergenceperiods: report of a WHO virtual scientificconsultation, September 2024ISBN 978-92-4-011146-2 (electronic version)ISBN 978-92-4-011147-9 (print version)© World Health Organization 2025Some rights reserved. This work is available under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0IGO licence (CCBY-NC-SA3.0IGO;https://creativecommons.org/licenses/by-nc-sa/3.0/igo).Under the terms of this licence, you may copy, redistribute and adapt the work for non-commercialpurposes, provided the work is appropriately cited, as indicated below. In any use of this work, thereshould be no suggestion that WHO endorses any specific organization, products or services. The useof the WHO logo is not permitted. If you adapt the work, then you must license your work under thesame or equivalent Creative Commons licence. If you create a translation of this work, you shouldadd the following disclaimer along with the suggested citation:“This translation was not created bythe World Health Organization (WHO). WHO is not responsible for the content or accuracy of thistranslation. The original English edition shall be the binding and authentic edition”.Any mediation relating to disputes arising under the licence shall be conducted in accordance with themediation rules of the World Intellectual Property Organization(http://www.wipo.int/amc/en/mediation/rules/).Suggested citation. Considerations for use of avian influenza A(H5) vaccines during theinterpandemic and emergence periods: report of a WHO virtual scientific consultation, September2024. Geneva: World Health Organization;2025. Licence:CCBY-NC-SA3.0IGO.Cataloguing-in-Publication (CIP) data. CIP data are available athttps://iris.who.int/.Sales, rights and licensing. To purchase WHO publications, seehttps://www.who.int/publications/book-orders. To submit requests for commercial use and queries onrights and licensing, seehttps://www.who.int/copyright.Third-party materials. If you wish to reuse material from this work that is attributed to a third party,such as tables, figures or images, it is your responsibility to determine whether permission is neededfor that reuse and to obtain permission from thecopyright holder. The risk of claims resulting frominfringement of any third-party-owned component in the work rests solely with the user.General disclaimers. The designations employed and the presentation of the material in thispublication do not imply the expression of any opinion whatsoever on the part of WHO concerningthe legal status of any country, territory, city or area or of its authorities, or concerning thedelimitation of its frontiers or boundaries. Dotted and dashed lines on maps represent approximateborder lines for which there may not yet be full agreement.The mention of specific companies or of certain manufacturers’ products does not imply that they areendorsed or recommended by WHO in preference to others of a similar nature that are not mentioned.Errors and omissions excepted, the names of proprietary products are distinguished by initial capitalletters.All reasonable precautions have been taken by WHO to verify the information contained in thispublication. However, the published material is being distributed without warranty of any kind, eitherexpressed or implied. The responsibility for the interpretation and use of the material lies with thereader. In no event shall WHO be liable for damages arising from its use.This publication contains the collective views of an international group of experts and does notnecessarily represent the decisions or the stated policy of the World Health Organization. ContentsAcknowledgements........................................................................................................vAbbreviations................................................................................................................viExecutive summary.......................................................................................................11. Introduction..............................................................................................................12. Characteristics of candidate human A(H5) influenza vaccines........................................4Methodology........................................................................................................4Landscape and pipeline.........................................................................................4Summary of the evidence of current landscape of A(H5) influenza vaccines....................4Summary of the evidence of development pipeline for new A(H5) vaccines....................8Safety: summary of the evidence..........................................................................11Immunogenicity: summary of the evidence............................................................11Cross-reactivity: summary of the evidence........................