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| Credit NIAID |
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As we discussed yesterday morning, twice each year influenza experts gather to discuss recent developments in human and animal influenza viruses around the world.
Yesterday we looked at the WHO's recommendations for next year's Southern Hemisphere seasonal flu vaccine, while today we'll look at their selections for the development of novel flu vaccines for those viruses that possess some degree of pandemic potential.Just as there are currently more than a half dozen subclades of seasonal H3N2 jockeying for dominance in the flu world (see The Enigmatic, Problematic H3N2 Influenza Virus), there are dozens of subclades and genotypes of avian and swine flu viruses competing in the wild.
Simply put, the H5N1 virus in Egypt (Clade 2.2.1.2) isn't isn't the same as the H5N1 virus in Nigeria (Clade 2.3.2.1c), or the one circulating in Bangladesh (Clade 2.3.2.1a).So, when we speak of the avian H5N1 virus, or H7N9 - we are really talking about multiple genetically distinct variants - each on their own evolutionary path. And a vaccine developed against one strain of the same subtype may not prove protective against another.
Since H5N1 emerged in 2003, more than three dozen H5N1 candidate vaccine viruses (CVVs) have been selected by WHO for development. While it can be expensive, having a proven CVV already tested and approved can save months of valuable time if mass production and distribution of a vaccine is ever required.
Similarly there are currently 14 H7N9 CVVs, and 7 H9N2 CVVs either developed or in the pipeline. Other novel viruses, including swine variant H1 and H3 viruses, have CVVs as well.The latest report from the WHO calls for 3 new CVVs (2 avian, 1 Swine variant) to be developed:
Influenza A(H5) candidate vaccine viruses
Based on the current antigenic, genetic and epidemiologic data, a new A/duck/Bangladesh/17D1012/2018-like A(H5N1) CVV is proposed.
Influenza A(H9N2) candidate vaccine viruses
Based on the current antigenic, genetic and epidemiologic data, a new A/Anhui-Lujiang/39/2018-like A(H9N2) CVV is proposed
Influenza A(H1)v candidate vaccine viruses
Based on the current genetic and epidemiologic data, a new A/Michigan/383/2018-like A(H1N2)v CVV is proposed.
The highly detailed full report can be read at:
Antigenic and genetic characteristics of zoonotic influenza viruses and development of candidate vaccine viruses for pandemic preparedness
September 2018
The development of influenza candidate vaccine viruses (CVVs), coordinated by WHO, remains an essential component of the overall global strategy for 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 genetically and antigenically, leading to the need for additional CVVs for pandemic preparedness purposes. Changes in the genetic and antigenic characteristics of these viruses relative to existing CVVs, and their potential risks to public health, justify the need to select and develop new CVVs.
This document summarises the genetic and antigenic characteristics of recent zoonotic influenza viruses and related viruses circulating in animals 1 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 website 2 .(Continue . . . )
