Vaccines: Creating alternatives to shark compound for vaccines

The generation of over 20 semi-synthetic analogues of squalene — a compound traditionally derived from shark liver oil and used to enhance the immune response of certain vaccines — is reported in a study published in npj Vaccines. The findings raise the possibility of being able to sustainably source replacements for this compound.

Shark-derived squalene has been used in vaccine adjuvant formulations (substances that are used to increase the efficacy or potency of some vaccines) in influenza and COVID-19 vaccines and is a key component in vaccine candidates under clinical evaluation for diseases including tuberculosis and malaria. However, shark populations have been subject to overfishing, and the global abundance of oceanic sharks and rays has declined by 71% since 1970, which may lead to problems with the supply of squalene.

Christopher Fox and colleagues generated over 20 squalene analogues from yeast-produced β-farnesene and evaluate their activity as vaccine adjuvant components compared to shark squalene. The authors found that several of the compounds produced (including alcohols A, farnesene thermal dimers, diols B, ether 4, and ether 5) possessed similar or improved adjuvant activity properties compared to shark squalene. Fox and co-authors suggest that some of these compounds could make promising alternatives to the use of squalene; however, additional testing would be necessary to advance such compounds in vaccine products.