Wolf are clearly afraid by humans. I doubt they would attack any of us in our alpine collecting trips ! :-)
This said, I don't see why they wouldn't attack a lost small kid or wounded man in the forest during the night. The probability is indeed very small and wolves represent no real risk to humans (who anyway are stupid enough to kill his own species...).
I am a pro-wolf person but it is true it is a huge issue for shepperds.