Horseshoe Crab Blood & COVID-19

by Bradley Knight 21 days ago in science

How 500,000 crabs are being harvested and drained of blood in the fight to find a coronavirus vaccine.

Horseshoe Crab Blood & COVID-19

A Horseshoe crab is a marine arthropod. Contrary to their name, they are not crabs at all. In fact, the Horseshoe crab is actually more closely related to spiders than they are crabs.

Horseshoe crabs have been around for melena and are considered as living fossils as their design has gone under relatively few changes in the past few million years.

So what is their relevance to the current pandemic you might be thinking? The answer to that can be found in their blood.

The Horseshoe crab is somewhat of a miraculous thing in the medical industry. Its blood is blue, and because of this holds central medicinal benefits for our species when dealing with vaccine contamination control. Which is crucial in our managing of pandemics such as the one we find our selves in today.

So what's so good about their blood? Unlike us, Horseshoe crabs use hemocyanin to carry oxygen through their blood, and because of the copper present in hemocyanin, their blood is blue.

This blue blood results in amoebocytes, which play a similar role as our white blood cells do in defending against pathogens. It's these amoebocytes which are used to make Limulus amoebocyte lysata (LAL). Which is used to detect bacterial endotoxins in healthcare applications (vaccines, treatments, medicine etc).

LAL acts as a natural test for purity when considering approving a medical solution for injection into the human body. Stock solutions of medicine are infused with LAL, which quickly acts as a clotting agent and binds any harmful microbial by-products and endotoxins within a solution to then be easily removed. This then preventing them from entering the manufacturing process and preventing us from exposure to harmful by-products when being injected with a vaccine.

It's not just the Horseshoe crab blood that's important to us. It's also their place within the food chain and their role in the marine ecosystem on the Eastern United States seaboard. They also serve as good bait for commercial eel and conch fisheries, which are massive contributors to the coastal eastern US economy.

As fantastic as Horseshoe crab blood is to our species. The use of it in our vaccines comes at a great cost, and Horseshoe crabs are constantly under assault.

In laboratory settings to harvest the blood for vaccines, an estimated 50,000 crabs die during the process. Which comes in at anywhere between 3-30% of individuals when approximately 500,000 individuals are drained of their blood each year.

It's widely understood that those that survive the blood harvesting process are returned to the ocean. Yet there is a growing scepticism amongst the scientific community that certain companies are instead seeling the crabs as fishing bait to compensate costs for lower yields being brought in yearly. This results in fewer individuals breeding. Which leads me to my final point.

As a result of overfishing, pollution, and habitat loss (coastal development) Horseshoe crab populations are seeing rapid declines.

This decline is only going to get worse as the demand for vaccines increases. Which given that we're currently in the middle of a pandemic, and a working vaccine is yet to be created. Demand is sky-high on a global scale. This surge in demand could result in catastrophic damages to Horseshoe crab breeding populations across the eastern USA as a vaccine for COVID-19 is saught after.

Companies currently harvesting Horseshoe crabs have said that the supply of crabs in the ocean is up to the task in accommodating the vaccine testing for COVID-19. Yet industry-specific information on the number of individuals needed is lacking transparency.

There is hope though, a synthetic alternative to LAL called recombinant Factor C (rFC), has promising results for Horseshoe population numbers. rFC acts the same as LAL, but its synthetic in origin meaning Horseshoe crabs don't need to be harvested for their blood, resulting in no deaths.

The only issue is that pharmaceutical groups across the USA like medical standards group U.S Pharmacopeia (USP) are failing to list this synthetic alternative rFC alongside the tried and tested LAL. With reasons for this being that rFC requires more testing, and the current LAL has a 30-year track record for safety and success. I'm sure this decision has nothing to do with the cost...

This comes as a blow to the industry and Horseshoe crab populations. Yet contrary to the USP ruling, rFC has been approved by the E.U for widespread use across Europe by the European Pharmacopeia.

What this means is that for now at least, LAL derived from Horseshoe crab blood is going to be used in the search for a COVID-19 vaccine in the US. Yet for the EU, research into a COVID vaccine will use the synthetic alternative, rFC. Resulting in a reduction of Horseshoe crab deaths.


If you liked this read, and want some more Ocean content in your life check out my Instagram: @marine.knight where I post beautiful sealife pictures and share mini-stories about my experiences with our mother sea. Thanks for reading.

Bradley Knight
Bradley Knight
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Bradley Knight

23 | Marine Biologist(ish) 🐠

Just a guy trying to be more open whilst trying to save the oceans.

Spread love and whatnot people ✌🏻

Hmu on Instagram if you like what I say - @marine.knight

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