Polysorbate 80 is used in many vaccines.
This document - Avantor's injectable grade Polysorbate 80 datasheet: http://askavantor.force.com/servlet/fileField?id=0BEG0000000TSTm
says: “Rev. 7; March 30, 2011 – Section 4: Added peanuts to the Allergen list; Corrected residual solvents info for Ethylene glycol; minor formatting. (JLW) ”
So Avantor was unable to guarantee that this Polysorbate 80 was not contaminated with peanuts, before 2011. Today, you will see Avantor specifically claiming their product is of non-peanut origin.
Documented evidence that vaccines have been contaminated with peanut proteins all along ...