Re: Canada stockpiling H5N1 vaccine

On 2/19/2025 5:12 PM, RonO wrote:

https://www.cidrap.umn.edu/avian-influenza-bird-flu/canada-announces- avian-flu-vaccine-buy-usda-confirms-first-h5n1-detections
 500,000 doses have been purchased.  Canada had the critical case of a teenager being infected with the D1.1 genotype.  They do not state what relationship that the vaccine has to the D1.1 genotype.  It is a subtype of the Asian H5N1 clade 2.3.4.4b, but the D1.1 genotype is a reassorted virus that Has the H5 gene of the 2.3.4.4b clade, but it has the N1 gene from a North American virus.  You would think that they would have tested the vaccine against the D1.1 variant before deciding to stockpile it.  If it is a different enough virus the vaccine may not work against the virus that they need to have a vaccine against.  As far as I know the D1.1 genotype has not yet been evaluated against the current vaccine H5 strains.  The initial B3.13 dairy genotype was neutralized by antibodies produced by the H5 vaccine strains, but that virus has changed quite a bit since and they haven't retested the current sequence variants.  They know that the vaccines would likely not have been that effective against the B3.13 virus that infected the Missouri patient, but they haven't reevaluated the current variants because they don't want to know the answer.  They already stockpiled a million doses of the H5 available H5 vaccine, but that stock pile may be worthless against D1.1 and the current B3.13 sequences.  Just like the covid vaccines had to keep changing they need to update the vaccines to the virus that are currently out there.
 The article also notes that rats and other mammals are being infected by the avian influenza, but they aren't disclosing what genotype.
 Ron Okimoto
 

https://www.cidrap.umn.edu/avian-influenza-bird-flu/h5n5-avian-flu-detected-canadian-poultry-flock-uk-seals
It looks like Canada has another H5 variant to worry about.  They have found H5N5 in poultry and the same genotype in the UK in seals.  This virus has the same H5 gene as the H5N1 variants clade 2.3.4.4b, but has reassorted with European avian influenza and has an N5 allele instead of the N1 allele.  The 2.3.4.4b clade is a couple of decades old, and the H5 sequences can be highly variable as long as they can be traced back to that lineage.  The UK is also stockpiling H5 vaccine, but there is no guarantee that the vaccines would be effective against the extant H5 sequences, especially since the other major antigen (N5) comes from another clade, and has an independent lineage.  It looks like the vaccine that they are stockpiling should be, at least, bivalent containing at least 2 viral variants.
Ron Okimoto