I had Canna Virus hit the Canna in the front garden last year. I had not bought any new Canna as so much stock was virused, but some kind soul obviously did, and they infected mine
I dug them all out and binned them as soon as I diagnosed what it was. Fortunately I caught it in time and those out back remained ok. The problem is, most people hang on hoping it will go away, but instead the Aphids spread the virus to other healthy canna. Seed is about the only way you can be sure, but you can't get named hybrids from seed.
Don't know what will happen if a Virused Canna is TC'd