Saoirse Ronan was at the red carpet opening of The Adventures of Tintin in Ireland and the TV show Xpose asked her about The Host. She mentions that Stephenie Meyer will be very hands on during the filming process. She also says that she is playing Wanda and Melanie.
There is no option to embed the video, so you will have to go to the website to watch it.
Source: XPose, The Host Movie Fans