Covid-19, the vaccine possible only thanks to the blood of a rare crab

Updated: Aug 3, 2021


Horseshoe crabs are not true crabs – they're more closely related to spiders, ticks and scorpions. Plant Image Library/C.C. 2.0




Knowing that modern medicine still depends on the blood of a bizarre and rare aquatic animal to check for bacteria in vaccines is a wonderful lesson for those who believe in the progress of the world, ignoring how biotechnology still relies on elements of nature.

For decades, pharmaceutical companies have used a component in the blood of horseshoe crabs to test injectable medicines, including vaccines: it is also happening for the one against Coronavirus.

As the BBC explains, «The horseshoe crabs have 10 eyes, have been around for more than 300 million years and we use their pale blue blood to try and save our lives. It is not science fiction, but simply a beneficial "old" science ». Every year, hundreds of thousands of these "living fossils", structurally similar to spiders, are captured and taken to American laboratories, where some of their blood is removed, before being released into the wild again. However, it was found that this practice reduces the possibility of mating in females.

A still from the PBS Nature documentary <i>Crash</i>PBS


30% of each crab's blood is drawn in some kind of weird milking, and it helps make sure there aren't any dangerous bacteria in the newly created drugs - the type of bacteria that can kill people even in small amounts. The extract in the crab's blood cells reacts chemically against harmful substances: which is why scientists use it to test whether new medicines are safe.

Environmentalists and some companies have pushed for a broad acceptance of an alternative test, to protect the horseshoe crabs and birds that feed on their eggs. Earlier this year, it looked like it was close to success as the non-government group that issues quality standards was approving an alternative test. However, the American Pharmacopoeia has announced that the alternative test known as rFC requires significantly more studies. In times of pandemic, it would be advisable to avoid wasting further research energy.