Charlatans at work.
IMO, you either spontaneously recover (the body is a wonderful machine) or the medication kicks in.
Prayer has no effect on the outcome.
All the prayers, chanting and laying on of hands will not speed recovery or lessen the chance of whatever outcome is diagnosed.
The fact that recovery cannot be duplicated to see whether faith played a part or whether you would have recovered sans faith, means that we will never, in truth, know the extent that the power of positive thinking has on the body.
IPlayer has an investigative programme which I found interesting. EXORCISM, the battle for young minds.