Conservationists fear the fight against COVID-19 could devastate the world's already fragile shark populations. A number of pharmaceutical companies are indeed using squalene, extracted from the liver of these fish, in the development of their vaccines.
In order to move in the water while expending a minimum of energy, fish must be in control of their buoyancy. To do this, cartilaginous animals like sharks have developed an oversized liver composed of several lobes and full of fats that lower the specific weight of the body. These oils include a fatty acid called "squalene".
Known for its moisturizing properties, this compound is commonly used to produce cosmetics and sunscreens. But remember that squalene is also used in some vaccines as an "adjuvant". In other words, as a pharmacological agent to increase the strength of certain drugs by stimulating the immune response of recipients.
As of September 29, approximately 17 of the 176 vaccines currently in full clinical and preclinical evaluation used adjuvants. And on this sample,five vaccine adjuvants are based on squalene.
One of them – MF59 – contains approximately 9.75 milligrams of squalene per dose , says Katie Camero for the Miami Herald . Note that this adjuvant has been used to combat Middle East respiratory syndrome (MERS) and SARS (severe acute respiratory syndrome).
If this adjuvant were used in a vaccine produced to treat the entire planet against Covid-19 with a single dose, then close to 250,000 sharks would have to be killed, estimates the non-profit organization Shark Allies. If two doses of vaccine were necessary, which is not impossible, nearly half a million sharks would therefore have to be sacrificed .
For Stefanie Brendl, founder and executive director of Shark Allies, this possible future dependence of the world's population on squalene could have a huge impact on shark populations, including many are already threatened by overfishing and the fin trade.
The squalene industry already kills around three million sharks each year , according to the nonprofit. Hammerhead sharks, great whites and whale sharks are among the most targeted species, but they are not the only ones. Deep-sea sharks, which therefore develop larger livers, are also highly sought after.
The problem is that these fish produce few young and are very slow to grow. This is why they are unable to compensate for losses due to human activities.
Shark Allies is obviously not demanding that pharmaceutical companies slow down or stop their work. On the other hand, she underlines the need to think about non-animal alternatives , such as yeast, bacteria, olive oil or sugar cane, which have varying levels of success as adjuvants.
These options, on the other hand, are more expensive (up to 30%), and the squalene extraction process takes longer . Stefanie Brendl nevertheless points out that the profits of pharmaceutical companies, inherent in the sale of these future vaccines, will be considerable. Also "it is reasonable to ask them to start thinking about reliable and sustainable production of these treatments" .
