I completed the MQ last night and fast traveled to whiterun which is the only place I ever encountered the traveler. He didn't appear but I may have "accidently" mistook Nazeem for him and now he's dead haha. But as I mentioned I was also using the amulet from Nexus. Guess we'll see. If I never see the traveler again then I know I should be safe from vampires appearing, other then Serana who refuses to be cured.
Im doing the Thieves Guild Quest at the moment including the jobs for Vex and Delvin, so im in and out of the cities alot, and the only encounter ive had with another Vampire was out in the wilds where a mistwalker vampire was taking out the Vigilants of Stendarr, she then had the bright idea to attack me and Serena, it turned out to be her last lol,
Even when i was getting some attacks in cities doing the Vampire questline, i never had the mysterious traveler, it was a Master Vampire with a thrall or death hounds, infact i had far more Dawguard attacks, which makes sense obviously lol, but since ive wiped the leadership out, ive had none of those either.