[6] Most plants, fungi, and animals produce squalene as biochemical precursor in sterol biosynthesis, including cholesterol and steroid hormones in the human body.

[16] In 2020, conservationists raised concerns about the potential slaughter of sharks to obtain squalene for a COVID-19 vaccine.

[11] An adjuvant using squalene is Seqirus' proprietary MF59, which is added to influenza vaccines to help stimulate the human body's immune response through production of CD4 memory cells.

[11] The Influenza vaccine business of Novartis was later acquired by CSL Bering and created the company Seqirus.

[23] An influenza vaccine called FLUAD which used MF59 as an adjuvant was approved for use in the US in people 65 years of age and older, beginning with the 2016–2017 flu season.

[25] Toxicology studies indicate that in the concentrations used in cosmetics, squalene has low acute toxicity, and is not a significant contact allergen or irritant.

[26][27] The World Health Organization and the US Department of Defense have both published extensive reports that emphasise that squalene is naturally occurring, even in oils of human fingerprints.

[11][28] The WHO goes further to explain that squalene has been present in over 22 million flu vaccines given to patients in Europe since 1997 without significant vaccine-related adverse events.