Squalene Adjuvants in Vaccines

by Joshua Soll

What are vaccine adjuvants and why are they relevant to shark conservation? 

Squalene is used as a moisturizing agent in cosmetics but why would it be in a vaccine? Squalene is used in some adjuvants which are a component of certain vaccines. Adjuvants are a common component of vaccines that are intended to increase a human body’s immune response to the vaccine, thus increasing its efficacy. Additionally, the inclusion of adjuvants in vaccines allows for less of the active vaccine ingredients/antigen (i.e. dead or weakened viruses or bacteria) to be needed and contained in a single dose. As a result, more vaccines can be produced. 

For many years, squalene-adjuvanted vaccines have been used to treat or prevent diseases such as different strains of influenza and coronaviruses (H1N1, H5N1, H7N9, H7N7, SARS-CoV, and MERS-CoV, influenza, and rabies). Some vaccines with a shark squalene-based adjuvant are currently being used in the market to prevent influenza. Additionally, there are companies such as GSK, Seqirus, and Clover Biopharmaceuticals, that are producing squalene-based adjuvants or using those adjuvants in the testing of COVID-19 vaccines. 

Several of the adjuvants used in COVID-19 vaccines currently being tested use shark squalene, while the squalene source for others are unconfirmed. MF59 is a common adjuvant containing shark-derived squalene that has been tested in the treatment of MERS-CoV, SARS-CoV, and in the use of an influenza vaccine. It is also currently being tested in COVID-19 vaccines. Since MF59 has been used as a component of other coronavirus treatments, it may be effective in COVID-19 vaccines. As a result, the demand for shark squalene could skyrocket, leading to a significant increase in the killing and harvesting of sharks for their livers. MF59 is only one of the adjuvants containing squalene that is being used in COVID-19 vaccine testing. (it is interesting to note that GSK has recently called MF59 the “pandemic adjuvant”, making this whole issue even more confusing.)

Why would a company choose to use shark-derived squalene in their adjuvants, over sustainable plant-based alternatives? The only answer we can see, which showed up in our initial research, is cost. It was found that olive-based squalene is approximately 30% more expensive than shark squalene. One of the reasons that shark squalene is believed to be cheaper is because of the ease of extraction of squalene from the shark. Squalene with a purity of >98% is obtained directly from the liver oil of a shark after a single distillation phase in a vacuum at temperatures of 200-230 degrees Celsius. This process takes  10 hours, whereas nearly 70 hours of processing are required to obtain olive oil squalene with a purity higher than 92%. Keep in mind that this is a comparison to just one type of sustainably sourced squalene, olive. We now know that extracting squalene from sugarcane is faster and more cost-effective than that of sharks. In addition, the purity of non-shark-derived squalene can be superior to that of shark squalene. As stated in our previous blog, “Alternatives to Animal Squalene,” squalene derived from sugarcane does not have the same impurities and it is more consistent than shark squalene, every single time. This is extremely important to know, especially when talking about the mass production of vaccines. 

Yeast-derived squalene, or biosynthetic squalene, is a whole different story. In a recent research paper, scientists found that “yeasts have several advantages such as ease of genetic modification, a large body of work in scaling bioreactor/fermentation processes, a prevalence of accessible infrastructure for scaling, and are a generally recognized as safe (GRAS) organism by the FDA31. The ability to easily genetically manipulate yeast also allows for more specific (or less complex) mixtures to be produced, allowing for easier purification.” You can read more about this paper and the results in our previous blog, Alternatives to Animal Squalene.

Beware of Mixed Messaging

MEDICAGO DEVELOPS A “PLANT-BASED” VACCINE. BUT WAIT….?

Quebec-based Biotechnology company, Medicago, announced earlier this year that they are developing a plant-based Covid-19 vaccine that uses GSK’s “pandemic adjuvant” (which is MF59, made from shark squalene). So how can a product be called plant-based when it uses shark squalene? By getting by on a technicality. The antigen portion of the vaccine is plant-based, but the adjuvant is not. Why they believe this is ethical is hard to understand. We have tried to inquire via multiple channels and have not received an answer.

THE ISSUE IS PICKING UP STEAM

When we first came out with the articles about sharks in vaccines, the response from the conservation community was very hesitant, fearing blow-back from the community. Understandably so, as it was in the middle of the pandemic in 2020 and no one wanted to feed into vaccine hesitancy or be seen as anti-vax. It is important to emphasize, once again, that Shark Allies is no way asking companies to slow down the process of a COVID-19 vaccine. Instead, we are asking these companies to replace the shark squalene in some of these vaccine adjuvants with alternative non-animal-derived squalene. It is important that people get vaccinated to get control over this virus. And we can do it in a way that doesn’t harm the environment in the process.

THE TIDE IS TURNING

More and more organizations are stepping forward to take a position on this issue. We hope that this trend will continue. TRAFFIC, one of the leading authorities on the international trade of wild plants and animals published their official statement: Global vaccination programmes at risk without careful stewardship of critical wild ingredients such as shark squalene. "Governments must prioritise the sustainability of their vaccination programmes if they are to prevent risks from an improper stewardship of wild ingredients used in vaccines."

*Please refer to our Science and Research page for all research backing these claims.