Vaccines being made to protect people from H1N1 flu may not be so healthy for threatened species of sharks, National Geographic News reported Dec. 29.
Millions of doses of the 2009 pandemic H1N1 vaccine contain squalene, which is extracted from shark livers.
More commonly found in beauty products such as skin creams, squalene can be used to make an adjuvant, a compound that boosts the body's immune response.
The World Health Organization recommends adjuvant-based vaccines, because they allow drugmakers to create doses that use less of the active component, increasing available supplies.
Olive oil, wheat germ oil, and rice bran oil also naturally contain squalene, albeit in smaller amounts. But for now squalene is primarily harvested from sharks caught by commercial fishers, especially deepwater species.
"The deepwater sharks targeted have extremely low reproductive rates, and many are threatened species," Mary O'Malley, co-founder of the volunteer-run advocacy group Shark Safe Network.
One species, the gulper, is listed as vulnerable on the International Union for Conservation of Nature's Red List of Threatened Species, meaning the species faces a high risk of extinction.
In 2006 the European Union imposed deep-sea shark fishing limits in the Northeast Atlantic, and the amount of shark squalene available on the market has since been reduced.
Although vaccines containing squalene have not yet been approved for use in the U.S., they are being distributed elsewhere, including Europe and Canada.
Novartis, which produces H1N1 flu vaccines containing shark squalene, did not answer National Geographic News’ requests for information about its squalene supply.
Manufacturer GlaxoSmithKline announced in October that it had received orders for 440 million doses of vaccine containing adjuvant.
And the adjuvant in GSK's vaccines—which have been administered in 26 countries so far—contains shark-liver squalene, company spokeswoman Clare Eldred confirmed in a statement.
GSK wouldn't reveal the name of its supplier or the annual quantity of shark squalene it buys. But Eldred told National Geographic News that the drug company takes about 10 percent of its supplier's total output.
A shark-squalene alternative isn't yet an option for adjuvant vaccine makers, according to GSK's Eldred.
The drug company is looking at other squalene sources, including olive oil.
But at the moment, she said, "We are unable to find an alternative of high enough grade."