Having had some (bad) experience with Creeping Charlie, I suggest
transplanting your Vinca to a temporary "safe haven" and spraying Charlie
with a strong dose of RoundUp Ultra --- not once, but as often as it takes
to wipe it out, since you almost certainly won't get it all the first round
(seeds yet to sprout). Then replant the Vinca after you're absolutely sure
Charlie is gone. Like poison ivy, you may need to do a little hand weeding
later, but it should only be an occasional skirmish, not an all out war.