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1. The lead section of the article could be improved to include a little more information related to the evolution of the virus rather than discussing aspects of the virus itself.
2. The section "Mechanisms of Evolution" needs a little more scientific data to bolster the ideas. I would recommend adding how various strains have utilized the mechanisms to change from year-to-year.
3. More information could also be given for the analysis section as well. More examples could be given as to how strains are believed to or have been proven to have evolved from ancestral strains from different species and areas geographically.