I go back and forth on this every year. I'm not getting it this year. I got it last year because my daughter was having surgery in November and we needed to travel to her, and I wanted the extra protection. Nearly 3 wks post flu shot, and 3 days before travel I came down with the flu...fever, malaise, upper respiratory congestion, pain yada yada. I did make it to her surgery, but it wasn't an easy trip and ironically, I was talked into getting the flu shot by my doctor who said, you know they won't let you fly with a fever.....well, we had to cancel our flights and drive.
I wish I knew why - but I seem to fare better without it. I am not out and about very much, so my exposure is generally limited. I hadn't thought about the other ingredients in the vaccine - someone said formaldehyde - which is apparently true - although it is in teeny tiny amounts. Still - I seem to be very sensitive to chemicals and medication, etc. so perhaps that is it. I figured it just triggered an immune system response that essentially was backwards. Just another unsolved mystery.