Sharks are killed to make effective vaccines. More may die as scientists develop one for COVID-19, conservationists warn

Conservationist groups are concerned demand for a coronavirus vaccine will strain an already taxed resource: sharks. 

Shark liver oil contains the natural occurring substance squalene. Scientists use squalene for adjuvants that are added to vaccines to enhance immune response and increase effectiveness.

“We are in no way prioritizing sharks over human health, but we simply have to ask why more sustainable squalene sources are not being considered as an option,” said Stefanie Brendl, founder of Shark Allies, a nonprofit group dedicated to the protection of sharks and rays.

In many shark species, 50% to 80% of the weight of their liver is squalene, according to Dr. Corey Casper, president and CEO of the Infectious Disease Research Institute. A single shark could yield up to 300 grams of squalene, enough for about 30,000 doses of vaccine adjuvant.

The oil in a shark’s liver helps regulate its buoyancy in the water. Deep-sea sharks, which have higher concentrations of oil in their liver, are sought by fishermen, as are large sharks in more shallow waters.

Shark Allies lists more than 50 species targeted for their livers. Though most are relatively obscure creatures of the deep ocean, others are more well-known, such as whale sharks, great white sharks and basking sharks – all of which are considered vulnerable or endangered by the International Union for Conservation of Nature.

Before the pandemic, about 3 million sharks a year were harvested for their livers. In a worst-case scenario, Shark Allies estimates 500,000 more sharks will be needed to meet COVID-19 demand.

That number is based on an assumption of every person in the world getting two doses of the vaccine made with a shark-based squalene adjuvant. Most candidate vaccines listed by the World Health Organization don’t contain that type of immunity-boosting agent, so the actual number of sharks needed for COVID-19 vaccines is likely to be far lower. 

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GSK is one of the few companies manufacturing an adjuvant with shark-based squalene to support multiple COVID-19 vaccine candidates. In a statement to USA TODAY, the company said research into squalene alternatives is ongoing, but they won’t be an option within the time frame of the pandemic.

“The amount of squalene that will be needed to manufacture the intended 1 billion doses of its adjuvant system represents a very small proportion of the animal-derived squalene used worldwide – the vast majority of squalene produced is used by other industries including the cosmetic industry,” GSK said in the statement. 

According to a study in 2012 by BLOOM, a nonprofit group that works to preserve marine life, about 90% of the world’s shark liver oil production feeds the needs of the cosmetics industry, which uses squalene – or its hydrogenated form, squalane – for its anti-inflammatory properties that reduce skin redness and swelling.

“Pointing to someone worse doesn’t really relieve your burden of doing the right thing,” Shark Allies’ Brendl said. “The numbers are a little bit out of proportion, but we should change the thing we can change especially when it’s in our control.”

More cosmetic companies are switching from shark-based to plant-based squalene. California-based biotechnology company Amyris created a plant-based squalene by fermenting sugarcane in Brazil.

Amyris CEO John Melo said the company could create the world’s supply for squalene in a matter of months at half the cost of harvesting shark livers. 

“We can do that all day long,” he said. “We can do a billion vaccines this month and the next month. We can do that on demand.”

The company developed a method by which it extracts a small amount of squalene from low-yield sources such as sugar cane and uses a chemical method to develop a semi-synthetic squalene that is amplified, according to Casper, who disclosed that the Infectious Disease Research Institute is working with Amyris for its “promising alternative.” 

Amyris has a long history of making squalane for cosmetics but has only recently begun producing squalene for pharmaceuticals. Its research suggests plant-based squalene performs at the same levelas that derived from sharks.

“Everybody in the world deserves to have access to a clean and sustainable vaccine without killing one shark,” Melo said.

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Though this semi-synthetic alternative exists, Casper said there’s no other natural resource that meets the demand for a COVID-19 vaccine because extracting squalene from a plant source can be “extremely limiting.” 

A study in 2014 in BioMed Research International found an entire olive tree would yield 16 grams of squalene, about 5% of the yield of a shark, enough for about 1,600 doses of vaccine. Olives are the most plentiful plant source for squalene.

“We are in crisis because we cannot source enough squalene from the only viable natural source (sharks), but with innovative methods, we can develop semi- or fully synthetic alternatives,” Casper said.

GSK said in its statement it’s committed to “exploring the potential for alternative sources of its raw materials when possible,” including non-animal-derived sources of squalene for use in adjuvants.

Brendl is aware it may be too late to stop using shark-based adjuvants for the immediateCOVID-19 vaccine push but hopes pharmaceutical companies can make the change by the second or third generations of the vaccine.

“We are not trying to stop anything … it’s just something that we should all in our conscious calculate and try to do better,” she said. “We can do both: We can take care of sharks and make this vaccine.”

Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT. 

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

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