Direct from the CDC's website: http://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.pdf
Read the last paragraph in section 2 (right hand column, just above section 3).
I read the part where it said it was harmless. Is that what you meant?
Note, it says “Some inactivated flu vaccine contains a very small amount of a mercury-based preservative called thimerosol.”
“Some inactivated flu vaccine contains a very small amount of a mercury-based preservative called thimerosal. Studies have shown that thimerosal in vaccines is not harmful, but flu vaccines that do not contain a preservative are available.”
This part I suppose