The Horseshoe Crab is Key to Making COVID-19 Vaccine, But It Comes With a Cost


Once a year during the full moon, thousands of horseshoe crabs emerge from the depths of the ocean and gather on the beaches on the Atlantic coast to perform a prehistoric ritual: spawning. Like clockwork, the horseshoe crabs repeat this ritual every year, which they had been doing millions of years before humans even existed. 

These days, the spawning horseshoe crabs attract a frenzy of creatures: hungry birds, reptiles, and humans who work for pharmaceutical companies. As the crabs conduct their business, teams of workers collect the creatures to harvest one of the most expensive substances on earth—the crustaceans’ blue blood. A gallon of the horseshoe crab blood costs roughly P3 million. 

Why Horseshoe Crab Blood is So Valuable

In World War II, wounded soldiers feared treatment, which was just as likely to kill them as combat because of endotoxin in unclean medical supplies and drugs. In 1956, scientists discovered that horseshoe crab blood is so efficient at detecting toxins and bacteria in various substances. 

Photo by Wikimedia Commons.

Horseshoe crab blood plays a crucial role in the development of most drugs and vaccines available today. Horseshoe crab blood is the only known source of an enzyme called limulus amebocyte lysate, which reacts to the tiniest amount of a bacterial toxin called endotoxin. If endotoxin finds its way to a vial of vaccine, the consequences could be fatal to the person who will receive it. 

Pharmaceutical companies around the world, including those in the Philippines, rely on horseshoe crab blood to ensure their products are safe. Humanity’s singular reliance on the prehistoric creature is largely underappreciated and untold. The global effort to produce a COVID-19 vaccine is not exempted. 

This year, pharmaceutical companies will gather up to 500,000 crabs to collect their blood, but just enough to keep them alive. When enough blood has been collected, the crabs are released back to the ocean so they can come back the next year to spawn again. 

The sad part is that many horseshoe crabs don’t survive the ordeal. Every year, fewer and fewer horseshoe crabs are returning to the shore to spawn. Climate change, pollution, and pharmaceutical harvesting of their blood contribute to their dwindling population in the wild.

According to National Geographic, there were 1.2 million horseshoe crabs that came to shore in Delaware in 1990. In just 10 years, that number has dwindled by more than half to 333,500. That number has remained roughly the same for the last 20 years. 

You might suggest to just breed the horseshoe crabs in captivity. They’ve tried, to no success. Very little is known about the feeding and breeding habits of the horseshoe crabs, and humans cannot replicate the natural conditions of the ocean where the crabs thrive. 

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As a keystone species, hundreds of marine animals, birds, and reptiles rely on the horseshoe crab for survival. Sadly, harvesting its blood kills as much as 30 percent of horseshoe crabs released back into the sea, according to a 2010 study

With all medical drugs, vaccines, and medical supplies relying on the horseshoe crabs, it is easy to say that the fate of humanity hangs on the survival of the 300-million-year-old crustacean. In our effort to stay alive, we are slowly killing off the one species that is helping us do it. 

Photo by Pixabay / Ckaras.

There is no clear sight when it comes to developing a vaccine for the ongoing pandemic, but one thing is sure: With accelerated efforts to produce the COVID-19 vaccine, the horseshoe crabs will feel the tremendous pressure of humanity’s desperate effort to find a cure. 

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Mario Alvaro Limos
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