My daughter had her flu shot last Friday. (9 yrs. old) She complained of the area where she had the shot hurt pretty bad for a couple of days. But I think she tensed up knowing it was coming and they say it hurts the muscle more when you tense it up for a shot. By Saturday afternoon she said she was exhausted and looked very pale, and had dark circles under her eyes. She asked to go to bed early Saturday night! So I as REALLY worried and even gave her a stress dose. I SWORE she was getting sick. She usually gets some side affect from the shot every year (runny nose and slight fever), some years she doesn’t. So I thought this year watch out. I even watched her through the night I was so convinced she was getting sick. By Sunday morning, after a good nights sleep, she was her perky self again. All her coloring returned and she was completely fine. This is why I always choose a Friday after school to get her a flu shot. It gives her body time to sleep well, and really be able to let the "shot" settle into her system nicely. But to answer your question, we haven’t heard anything about it making people sick, or being short of it, or anything.