Commonground
Senior Moderator
September 2025
The development of influenza candidate vaccine viruses (CVVs), coordinated by the World Health Organization
(WHO), remains an essential component of the overall global strategy for influenza pandemic preparedness.
Selection and development of CVVs are the first steps towards timely vaccine production and do not imply a
recommendation for initiating manufacture. National authorities may consider the use of one or more of these
CVVs for pilot lot vaccine production, clinical trials and other pandemic preparedness purposes based on their
assessment of public health risk and need.
Zoonotic influenza viruses continue to be identified and evolve both antigenically and genetically, leading to
the need for additional CVVs for pandemic preparedness purposes. Changes in the antigenic and genetic
characteristics of these viruses relative to existing CVVs and their potential risks to public health justify the
need to develop new CVVs.
This document summarizes the antigenic and genetic characteristics of recent zoonotic influenza viruses and
related viruses circulating in animals1 that are relevant to CVV updates. Institutions interested in receiving these
CVVs should contact WHO at gisrs-whohq@who.int or the institutions listed in announcements published on
the WHO website2
.
Continued: https://cdn.who.int/media/docs/defa...r-pandemic-preparedness.pdf?sfvrsn=53d7cd36_6
The development of influenza candidate vaccine viruses (CVVs), coordinated by the World Health Organization
(WHO), remains an essential component of the overall global strategy for influenza pandemic preparedness.
Selection and development of CVVs are the first steps towards timely vaccine production and do not imply a
recommendation for initiating manufacture. National authorities may consider the use of one or more of these
CVVs for pilot lot vaccine production, clinical trials and other pandemic preparedness purposes based on their
assessment of public health risk and need.
Zoonotic influenza viruses continue to be identified and evolve both antigenically and genetically, leading to
the need for additional CVVs for pandemic preparedness purposes. Changes in the antigenic and genetic
characteristics of these viruses relative to existing CVVs and their potential risks to public health justify the
need to develop new CVVs.
This document summarizes the antigenic and genetic characteristics of recent zoonotic influenza viruses and
related viruses circulating in animals1 that are relevant to CVV updates. Institutions interested in receiving these
CVVs should contact WHO at gisrs-whohq@who.int or the institutions listed in announcements published on
the WHO website2
.
Continued: https://cdn.who.int/media/docs/defa...r-pandemic-preparedness.pdf?sfvrsn=53d7cd36_6