Horseshoe Crabs and Vaccine Safety Testing

U.S. regulatory policies for vaccine safety testing lag behind the science, resulting in a reliance on the blood of the horseshoe crab.

The process by which the crabs’ blood is taken is not only harmful to the animals, but it also introduces the risk of supply disruption. Fortunately, there is a nonanimal, synthetic option. And it’s better.

How Vaccine Safety Testing Hurts Horseshoe Crabs—And Why It Doesn't Have To

All injectable therapies and vaccines must be batch tested for fever-inducing contaminants before they are administered to humans.

The default test uses horseshoe crab blood, but a scalable, synthetic nonanimal test, called recombinant factor C (rFC), has been shown to be scientifically superior. Unfortunately, regulatory policies in the U.S. make it more burdensome to use rFC, compared to the traditional horseshoe crab blood test.

The European Pharmacopoeia has accepted rFC without the additional barriers that exist in the U.S., but most companies are global, so they default to conducting the test that is accepted by all regulators (to avoid duplicative work). The U.S. Pharmacopoeia still does not accept rFC without extensive additional work—work that is not required when using the horseshoe crab test.

Notably, the FDA has accepted rFC for certain Eli Lilly therapies, as this trailblazing company undertook extensive extra work in order to avoid using horseshoe crab blood. For two years, patients in the U.S. have been treated with injected drugs that were released based on safety data derived from rFC; no medical issues have occurred as a result.

The Physicians Committee is working directly with Congress and regulatory agencies to ensure that, in time, all batches of injectable drugs and vaccines, including those against COVID-19, are tested using nonanimal methods, without horseshoe crab blood.