Several companies competing for a coronavirus vaccine have encountered a new and unexpected hurdle: Activists protest against the use of a substance derived from sharks in their products.
The oily compound, called squalene, is secreted by shark livers and has immunity-boosting powers, which has led several companies to use it as a part of vaccines. A group called Shark Allies has launched a campaign calling on the Food and Drug Administration and other regulators to stop sourcing the compound from sharks. She warned that the mass distribution of a coronavirus vaccine could require the removal of tissues from more than 500,000 sharks.
The call to action made headlines around the world. But the story of shark squalene is not as straightforward as it may seem at first.
Why are some people so upset about sharks and vaccines?
Companies commonly use squalene as a moisturizing additive in cosmetics and sunscreens. Occasionally, however, the substance has also been used as an adjuvant in vaccines – a chemical that activates the immune system and promotes stronger and longer-lasting protection against disease.
While adjuvants aren't required for all vaccines, they can make or break certain prescriptions. By boosting the immunity of the products, they can also increase the efficiency of immunization by making more money on the ingredients of the vaccine and freeing up supplies for more doses.
Shark liver is among the best sources of the compound. According to Catherine Macdonald, a Florida shark biologist, between 63 and 273 million sharks die by human hands each year, and at least a few million of them are made from liver oil.
Two of the companies that Shark Allies studied are GlaxoSmithKline and Seqirus, which each make adjuvants that contain around 10 milligrams of squalene per dose. These ingredients are found in a number of coronavirus vaccines currently being tested in humans, including products from Sanofi, Medicago, and Clover Biopharmaceuticals, all of which have partnered with GSK.
It is estimated that between 2,500 and 3,000 sharks are needed per ton of squalene. Shark Allies were extrapolated from these statistics to arrive at their frequently cited numbers, which show the potential ecological burden on sharks.
Are the Shark Allies numbers realistic?
Such estimates are difficult to make.
Dr. Macdonald pointed out that sharks – of which there are more than 500 species worldwide – differ in size, weight, and liver squalene levels. The number of sharks it takes to get enough squalene adjuvant vaccine doses to treat all of the people on earth is therefore likely to be a "huge range," she said. Your own calculations for this statistic range from tens of thousands to more than a million, depending on how many doses are needed per person.
It is also true that of the dozen of vaccine candidates in human clinical trials, most do not contain squalene. To rely solely on vaccines that use shark-based squalene, "a lot of other promising candidates would have to fail – they would have to be the last vaccines," said Saad Omer, a vaccines expert at Yale University. A more plausible scenario would likely involve the distribution of multiple products made by multiple companies.
Are there alternatives to shark oil?
Squalene has many plant and animal sources (including people who produce it to lubricate and protect their skin).
However, squeezing squalene out of plants is a pain, while “Shark oil is cheap and easy to get,” said Stefanie Brendl, CEO of Shark Allies.
"We think that's not an excuse," she said.
She pointed to Amyris, a California-based company pursuing a synthetic alternative.
Evan Berland, director of US corporate communications at GSK, said the company "is committed to protecting the environment and is actively exploring the potential for alternative sources of raw materials when possible."
However, "within the time frame of the Covid-19 pandemic," no squalene alternatives would be available, he said.
Joanne Cleary, a seqirus spokeswoman, said her company was in a similar situation. "More needs to be done to research herbal or synthetic alternatives before they can be used in vaccines," she said.
Exchanging adjuvants or even sources of adjuvant is not trivial, said Dr. Omer. Every product needs to be refined and tested to ensure that it is safe, effective and, often tediously, working through the necessary regulatory steps.
Are Vaccine Manufacturers Responsible for Harvesting Shark Squalene?
Neither GSK nor Seqirus named their suppliers. But GSK said the sharks that their squalene came from were "usually caught for other purposes."
Dr. Macdonald said it was impossible to answer questions about the exact number of sharks that were explicitly killed for their squalene. Fishermen catch sharks for their meat or fins, or simply as bycatch; In many cases, the oil drawn from their bodies may otherwise have been thrown away.
So should you really be worried that coronavirus vaccines will mass destroy sharks?
Even the Shark Allies team doesn't believe the vaccine industry “hunts sharks – we're not saying that at all,” said Ms. Brendl. They also don't want companies to stop or delay production of coronavirus vaccines.
"But there are alternatives to shark adjuvants," she said. "Start testing them."
Dr. Macdonald and others noted that vaccine manufacturers are by no means primarily responsible for hoarding shark liver oil. Most squalene from fish is still passed into cosmetics – "much less important things" than vaccines, said Jasmin Graham, a shark biologist at the Mote Marine Laboratory in Florida.
Developing more sustainable fishing practices could help address several problems at once.
"I don't think we should demonize the people who are trying to save our lives," said Ms. Graham. "There are much bigger, more important hills to die on."