Animals and the Making of Human Vaccines

We know the names of certain famous scientists like Louis Pasteur, who developed the vaccine for rabies with his research team in the 1880s. But there are more than people to this story.

Pasteur is posing with these white rabbits who represent the rabbits used to create the first rabies vaccine. He and his assistants would use the animals to create a weakened (attenuated) form of the virus that could be used in other animals and people to prevent the disease even after exposure.

Rabbits were not the only animals in Pasteur’s lab. He kept rabid dogs as a source of the virus, and monkeys were initially used instead of rabbits in his experiments.

Animals were important laboratory tools that served both as a reservoir for the rabies virus and a way of transforming it from a deadly pathogen to a medical product.

The idea to use disease material from a non-human animal in humans to prevent disease was not a new concept in Pasteur’s time.

The smallpox vaccine was developed from cowpox virus by Edward Jenner in the late 18th century, and cows were often used in the production of the smallpox vaccine until the disease was eradicated in the late 20th century.

The fluid from cowpox pustules would be drained, purified, and injected into people.

The word vaccine is derived from the same Latin root as the word for cow, vacca.

Originally, the term referred specifically to using cowpox material in humans to prevent smallpox. Only after Pasteur used the term for his rabies treatment nearly a century later did it become detached from its bovine origins.

In the 19th and 20th centuries, animals at pharmaceutical companies and medical facilities—such as cows and horses—were bred, raised, and kept not for milk, meat, or transportation but to make the medicinal products that protected people against epidemic infectious disease.

At the Eli Lilly and Company Biological Plant, the horses were the plant equipment. They produced diphtheria antitoxins (antibodies) that were harvested by technicians.

After the desired material (pus, blood, spinal cords, etc.) was extracted from the animal, it was processed in laboratories like the ones depicted in this article.

The resulting product would be introduced into humans, most often by injection.

While animals were not visible by the time someone received a vaccine, it did not mean that people were not aware where their vaccines came from originally. People knew that the diphtheria antitoxin came from horse serum, the rabies vaccine from rabbits, and the smallpox vaccine from cows. 

Some anti-vivisectionists (people who oppose animal experimentation) refused to get vaccinated or treated for these diseases because animals were used or killed in the production process.

Some worried about what would happen when foreign animal matter was introduced into the human body. This was just one reason people objected to vaccination. Others opposed it for religious, moral, or medical reasons.

Rumors about horrible side effects were spread by opponents of vaccination in pamphlets, speeches, and by word of mouth. While no one who received the smallpox vaccine birthed a cow or had one erupt from their nose, there were possible negative side effects.

Quality control was difficult to achieve in the late 18th and early 19th century when the vaccine was first introduced and could be contaminated or too weak to provoke an immune response.

Vaccine skeptics and resistors still use arguments about the origins of vaccines and the fear of introducing foreign matter into the body. Like those who fought against smallpox vaccines, they claim that this material will fundamentally change the human body.

While some people rejected vaccines, many more during the 19th and 20th centuries sought out vaccines to prevent and treat diseases.

Although this image pokes fun at people as seeking a vacation and a vaccine, it was because people traveled from around the world to line up outside of Pasteur’s lab for a rabies vaccine made from rabbits.