I know IMDB is no proof. The TWD maker won't delete their actors of the cast list before the audience sees that a character dies. It would destroy all the surprises.
I try to keep an eye on the twitter/online presence of the actors.
And here we got:
This photo of an article last months...someone pointed on Melissa's hair, that it was growing in her neck. (But it's her outfit of the first episodes)
I was even happier about this photo of BoldtKeith. He twittered that he met Melissa only a few days ago in Senoia. So she is still around. I hope she is still filming for TWD.