Reviewer response for version 1
The authors provide an analysis of HA sequences of recent H3N2 influenza viruses from the ongoing season using the protein sequence-based clustering algorithm ISTREE. 
This method has been developed and published by one of the authors several years ago. 
ISTREE seeks to combine molecular data and provide a clustering with respect to antigenic relatedness of the influenza virus HA. 
Previous publications provided a retrospective analysis of genetic and antigenic data. 
Basically, ISTREE is advertised as an alternative to antigenic cartography of influenza viruses using serologic data based on hemagglutination inhibition (HI).
In fact, such algorithms would be of great interest and value in terms of vaccine selection. 
The prospective statements re appropriate vaccine strains for a future influenza season made by the authors here are quite clear but they are solely based on ISTREE assessments. 
No flanking/supporting data based on standard HI assays is provided. 
Assessing the validity of the ISTREE data therefore is not possible. 
The data may well turn out to be useful but, as it currently stands, they may be totally misleading as well.
Solid antigenic data will be required to validate the potentially useful ISTREE algorithm.
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