I put this into a comment but it deserves a wider readership.
Squalene is found in foods and your body makes it and uses it on the pathway to making cholesterol, which is a precursor to vital hormones. Your own blood contains sqalene. It is sold as a food supplement in the form of shark’s liver oil. Traces found in vaccines where it is not added appear to come from the oils left by fingerprints on laboratory glassware. The amounts found are far less than the concentration already in human blood.
The anthrax vaccine given to U.S. soldiers used aluminum hydroxide as an adjuvant. The purpose of an adjuvant is to boost immune response and allow us to use less of the antigen (disease substance that we want to become immune to). The U.S. doesn’t use squalene as an adjuvant in any vaccine. See this Q&A paper from the U.S. Food & Drug Administration (Portable Document Format file).