Challenge for the pandemic franchise.

We've read Pandemic and how Twilight cured ETS (EQUINE TRANSFORMATION SYNDROME) but before a portion of the population were ponified. And trapped several in midtransformation. We even read at least one story of the post pony pandemic world.

ETS was wiped out!.

But what every body overlooked was Sunset Shimmer used influenza (aka the common cold) as the medium for the transformation spell. What would happen if the cold virus mutated and started transforming those half transformed souls in Anthro ponies?

This is my challenge.