CDC has released results of the partial genome assay of the isolate obtained from the index patient in the Missouri hospital outbreak.  Due to limited availability of material from the patient, only the hemagglutinin, matrix and non-structural genes were sequenced.

 To date, assays confirm the isolate as an H5N1 influenza virus of the 2.3.4.4b clade.  Two amino acids substitutions were identified in the HA sequence considered to be unique to the specific patient but would not be associated with contagion.  There was no evidence that the virus would be refractory to antiviral drugs.  Molecular virologists are now evaluating the significance of the A156T mutation in the hemagglutinin gene.