An acquaintance of mine sat in a room waiting for a bus, it was not a spacious room, just a regular flat room. In front of her sat a boy who had chickenpox, from what she is telling me he looked normal but a bit pale, he also had ointment applied on his rashes, they sat in the same room for about 15 minutes before they boy left, she has not caught chickenpox during her life yet and she is 20 years old as well, So I wanted to ask how likely is it that she has caught it?