I've been maining Vlad recently, but I can tell you this: consistent ranged damage does a lot of good. Tristana, played smart, can do well against vlad. Others have said Kog'maw, and I actually agree. If you know how Vlad plays, you can bait him into harassing you, then punish him with E+W autoattack, and Kog farms way better than Vlad does, so if he has to play safe, he can do so effectively.
Morde is another good choice, but again, needs to play smart. Vlad's q may not damage through the shield, but it DOES restore life. Again, the key is to farm. And if the Vlad is smart and tries to wear down your shield through autoattacks, get in his face. He's not going to be willing to keep trying in a head-on fight.
Also of note: Vlad is at his most vulnerable pre-level 6. His q needs to be at 5 to be really spammable, and that's not until level 8 or so.
Heimer, I don't think is a great counter. I generally farm heimers easily as Vlad. Annies, Anivias, and Ryzes who know what they're doing, on the other hand, SUCK. Any burst caster with CC, really.
Like I said, consistent range DPS, or as I just mentioned, HEAVY burst casters with CC.