Wild animals used in vaccine tests: What's being done to help

A blog by Chloe Stevens, our scientific officer for our Animals in Science department.

We've all been excited to hear the recent good news about potential vaccines for COVID-19. But did you know that vaccine production relies heavily on the use of animals, not only in the laboratory but also in the wild? In particular, a unique, wild animal known as the horseshoe crab.

Vaccines, injectable medicines and medical devices all have to undergo several safety tests before they can be safely used, and one key test involves the blood of the horseshoe crab. As a result, we find ourselves as a society, facing an ongoing ethical dilemma; animal testing and animal use in laboratories as the cost for potentially life-saving medical treatments.

How horseshoe crabs are used to test vaccines

Research carried out by Dr Rich Gorman of the University of Exeter, funded by the Wellcome Trust and supported by our Animals in Science department, is helping to shape future discussions about horseshoe crabs and vaccine testing. But first, what is a horseshoe crab and why are they currently used to create safe vaccines?

Atlantic horseshoe crabs are found on the East coast of the USA and around the Gulf of Mexico. Each year, over 500,000 crabs are caught and taken to laboratories, where up to 40% of their bright blue blood is taken to be used to detect impurities called endotoxins in medicines and vaccines.

Why? Crab blood contains cells which react when endotoxins, produced by bacteria, are present. Endotoxins can be a serious threat to health, so this safety test is essential.

Animal testing and vaccines: Our welfare concerns

Sadly, this practice of blood extraction is not very animal welfare-friendly. The crabs are caught and kept out of the water while they're transported to the lab. They're then restrained to have their blood removed, during which they can become stressed and may also be crushed or injured. The crabs are then released back into the wild - but it's thought that up to a third may then die.

We believe that the crabs experience distress and suffering throughout this process - but unfortunately, some people don't accept that horseshoe crabs can suffer. To make it worse, horseshoe crab use is not covered by animal protection laws.

As well as animal welfare issues, the use of horseshoe crab blood also raises environmental concerns. The number of horseshoe crabs found in the wild is decreasing, which affects shorebirds who rely on horseshoe crab eggs as a major food source.

As global demand for medicines and vaccines grows, it's likely that this practice will become unsustainable. While it might be easy to turn away from this hard truth, this issue affects us all - anyone who has received an injection has been a consumer of horseshoe crab blood, regardless of how you feel about animal research and testing.

What are the alternatives to horseshoe crab blood?

So, the million-dollar question is - what can be done to help horseshoe crabs? The most promising solution is an alternative called the rFC test which doesn't use animals, and might even be able to replace horseshoe crab blood entirely. We believe this should be the primary goal for everyone involved.

The rFC test has been around since 2003, but there are debates over how well it can detect impurities, and although regulators in the EU have accepted it as a replacement test, the USA has not. Other alternative tests which don't use animals are also being developed, and new technologies can be used to reduce the amount of blood needed. The good news is that progress is truly underway.

How we're helping to improve the treatment of horseshoe crabs

As well as discovering alternatives to the test using crab blood, it's vital that steps are taken to reduce any potential suffering the crabs might experience. This could be easily achieved by handling them more gently and carefully, keeping them out of the water for shorter periods, and taking less blood from each individual. It's thought that these simple changes could halve the number of crab deaths following capture and blood removal.

Although these changes are a step in the right direction, there's more to be done. Horseshoe crab blood has been used successfully for a long time, so even after regulatory approval, it's possible that there'll be debates over whether the new rFC test is safe and suitable to replace the horseshoe crab test.

Until horseshoe crabs can be completely replaced with non-animal alternatives, it's really important that there's more recognition of the need to treat these remarkable animals with more respect and care, to think about their welfare, and to commit to protecting their numbers in the wild.

Our stance on animals in laboratories

Replacing all animal experiments with humane alternatives is the primary aim of our work. Sadly, this isn't something that can be achieved overnight, due to current scientific limitations. Until it is, our experts will continue to work with those involved in the regulation, care and use of lab animals (in the UK and internationally) to replace animals wherever possible, reduce animal use and suffering, and improve lab animal welfare.

Did you know?

1. Horseshoe crabs have been around for so long that they're sometimes referred to as 'living fossils' - the earliest horseshoe crab fossils are over 450 million years old! That's 200 million years before the dinosaurs!

2. The name 'horseshoe crab' is a misnomer - they're actually thought to be more closely related to spiders!

Find out more about horseshoe crabs and vaccines

Want to find out more about this research? You can read the full report, or take a look at our infographic all about horseshoe crabs, how they're used in science, our concerns and our most promising alternatives.

Find out more about animal testing and vaccines.

Infographic created in partnership with the Animal Research Nexus, funded by the Wellcome Trust and designed by Little Seed Design.

*Endotoxins can cause serious side effects including blood poisoning. If you, or your pets, have ever had an injection, you're a consumer of horseshoe crab blood.