What we know
According to our research, peanut oil is not referenced in any of the FDA-approved vaccine package inserts.
In 1964, The New York Times ran a story called PEANUT OIL USED IN A NEW VACCINE. The story ends with "Their patent is No. 3,149,036"
Some claim that because the 1964 NY Times article points out that "The new vaccine is still under study and is not yet licensed for general use" - it therefore must be that peanut oil was never used in vaccines.
But is that true? Since the article was first published in 1964, 60 years have passed and US patent 3,149,036 has been cited by 29 patents.
What we don't know
We don't know if any of the referencing patents make use of peanut oil and have ever been used in a US licensed vaccine.
Another reason it's not possible to say with confidence that peanut oil is not and never has been in a US licensed vaccine is that some ingredients are trade secrets and kept confidential. The FDA does not require vaccine manufacturers to make public every ingredient in a vaccine - some may be kept secret. This is documented on page 71 and page 77 of the 6th edition of the textbook Vaccines by Plotkin, Orenstein and Offit:
The term additive refers to materials that are added by the manufacturer for a specific purpose. Additives include adjuvants, preservatives, and stabilizers, as well as materials that are added to affect pH and isotonicity... Some information regarding additives and residuals is considered to be a trade secret and thus confidential.