It's rampant here at my site here in Allegeny Co, but prb'ly because it's supported by a large, local population of Siberian & Slippery elms, and the resulting hybrids. Killed my Valley Forge elm, and is slowly killing Sib x Slippery elms along my border stream. The pure Sib elms seem to be resistant, but act as carriers. My 35' Chinese elm got some inexplicable, nasty lesions on its trunk/branches yrs ago, but healed them over & is now fine. I reckoned that was an unsuccessful attack by the elm yellows.

If you don't have a significant population of other elms in your locality, it might not be an issue.