Sharks have made international news after Shark Allies, estimated that half a million deep-sea sharks are needed to extract enough squalene for Covid-19 vaccines. The non-profit organization recently came out with the petition to “stop using sharks in a coronavirus vaccine” and use more sustainably sourced alternatives.
But what exactly is ‘squalene’ and why is it possibly in human medicine? Well, first you need to look at basic shark anatomy. Sharks have no swim bladder, unlike bony fish, to help with buoyancy. So, they rely on the lift from their pectoral (side) fins and their large livers that are saturated with oil to maintain their buoyancy in water. Some sharks have a high content of the component squalene (C₃₀H₅₀) in their liver, a highly unsaturated aliphatic hydrocarbon.
According to the Food and Agriculture Organization (FAO), squalene has been/is being used as a “bactericide, an intermediate in the manufacture of pharmaceuticals, organic colouring matter, rubber, chemicals, aromatics, in finishing natural and artificial silk and surface active agents.” Nowadays, squalene is also being used in some adjuvants — common ingredients in vaccines that help create a stronger immune response. What is an adjuvant and why is it added to a vaccine? The Centers for Disease Control and Prevention (CDC) defines an adjuvant as “an ingredient used in some vaccines that helps create a stronger immune response in people receiving the vaccine.” In other words, adjuvants help vaccines work better by helping the body produce an immune response strong enough to protect the person from the disease they are being vaccinated against. The CDC website says that MF59 is a common adjuvant that contains shark-derived squalene. It’s currently found in the Fluad influenza vaccine, licensed for adults 65 or older, and has been used in USA flu vaccines since 2016 with an “excellent safety record.” According to the World Health Organization (WHO), since 1997 a dose of the influenza vaccine (such as FLUAD or Chiron) contains about 10 megagrams of squalene “to make the vaccine more immunogenic.”
According to Shark Allies, the MF59 adjuvant “has been used as a component of other coronavirus treatments,” which they are saying might mean it is effective against Covid-19, as well. Dr. Catherine Macdonald, Director of Field School and a Lecturer at the Rosenstiel School of Marine and Atmospheric Science at the University of Miami, confirmed this claim: “At least some of the vaccines in trials now use a shark-derived squalene adjuvant.” Looking at the 34 candidate vaccines in clinical evaluation and 142 vaccines in preclinical evaluation provided by a recent WHO report, five use adjuvants that are shark squalene based (GSK, Clover Biopharmaceuticals, Seqirus/University of Queensland/CSL, Medicago Inc. and Farmacologós veterinarios SAC/Universidad Peruana Cayetana Heredia).
Sharks that live in the deep sea tend to have more oil in their livers, and thus squalene fishermen target them (e.g. gulper sharks, basking sharks, and tope sharks). Shark-derived squalene not only yields the most oil but compared to other alternatives it is easier to extract and significantly cheaper. But these deep-water animals are particularly vulnerable to exploitation through overfishing because most grow slowly and reproduce infrequently. A 2011 report published by the Food and Agriculture Organization shows that these fisheries, which operate in the Indian, southeastern Atlantic, and western Pacific oceans, are also largely unregulated. Macdonald says Shark Allies estimate of “nearly three million sharks” being killed yearly to extract squalene is not unrealistic, adding, “It is realistic to say that the livers of more than three million individual sharks per year are harvested and traded, but it’s difficult to identify whether each shark is being killed ‘for’ squalene, as some individuals may have their livers harvested after being caught as bycatch or in fisheries primarily targeting sharks for fins or meat.”
Could up to 500,000 sharks be killed for Covid-19 vaccines, as Shark Allies states? Dr. Macdonald says, “I’m not sure the number of sharks harvested for a vaccine is the central issue. Shark-derived squalene is in use as a vaccine adjuvant—so where a more environmentally friendly and sustainable alternative exists, why wouldn’t we use it? From both a conservation and human health perspective, why would we want vaccine production to be potentially vulnerable to stock collapses?” Leonardo Guida, a shark expert with the Australian Marine Conservation Society (AMCS), agrees and that “the last thing we should do risk the health of our oceans – our life support system – any further.” Researcher Laurel Bristow, Clinical Research Coordinator III for Hope Clinic of the Emory Vaccine Center, also believes that the public pressure could cause the companies to change their squalene collection method. “But it all depends on which vaccines actually come to market, because none of the current front runners use any adjuvants at all.”
Thankfully, there are alternative solution rather than using shark-derived squalene: squalene is also found in plants with sources including olive oil, rice bran, wheat germ and amaranth seeds. In fact, the biotechnology company Amyris produces squalene from sugarcane to for the beauty industry! Shark Allies suggests using sustainably sourced squalene/non-animal alternatives in the pursuit of vaccine developments. “Using sharks in Covid-19 vaccines is short-sighted, unpredictable, and unsustainable. There are better alternatives,” reads the online petition. The petition is addressed to numerous entities, such as the U.S. Food and Drug Administration, European regulators, China’s National Medical Products Administration, and various vaccine developers in the pharmaceutical industry. These organizations have made no comment to date.