I'm afraid I can't give a better answer than Daisy's.

Daisy's answers are all correct when we talk about actual fear. However, there is another use of "I'm afraid" that doesn't mean "fear"—it means "regret." So you might tell someone, "I'm afraid John is not in his office today because he's on a business trip," or "I'm afraid the package won't arrive until next week." It's another way of saying "sorry, bad news." When used in this way, we don't need any prepositions.

" afraid of " e.g. I am afraid of spiders. (=feeling fear) " afraid to +V." e.g I am afraid to go out alone.(=unwilling to do something for fear of the consequences ) "afraid for" e.g. He was suddenly afraid for her. (=anxious about the well- being or safety of someone )