The History of Vaccines and the Importance of Vaccine Mandates

Part 3: A Safer Procedure and the Rise of New Vaccinations

Many stories of the advancement of science are told as epiphanies of a lone scientist and their individual struggles. For instance, Newton observes an apple falling from a tree and, in some sense, “discovers” gravity. Rarely are such stories objectively true in the sense of their simplicity and directness. Another story like this involves the invention of the first vaccine. As the story goes in 1796 an English country doctor named Edward Jenner noted that milkmaids rarely became infected with smallpox, or if they did, the symptoms were slight. Often, the milk maids had been previously infected with a less virulent sickness, cow pox. This gave Jenner an idea. Could he inoculate people with the less dangerous cowpox residue, instead of the more dangerous small pox residue, and confer immunity against smallpox in the recipients? As a test he used a method similar to variolation on the child of his gardener, an 8-year-old boy named James Phipps. Instead of using small pox residue, he used residue from a milk maid infected with cow pox. When he later twice exposed the boy to small pox, the boy had no reaction, not even the common mild sickness that commonly accompanied inoculation.  Jenner hypothesized that this method would confer immunity from smallpox to a wide range of patients. He called this new method vaccination from a combination of the latin words for cow (vacca) and cowpox (vaccinia). It turned out that this procedure was indeed more safe and effective.

Edward Jenner

However, Jenner was not the lone pioneer he has been made out to be. Jenner was the apprentice of a physician named Daniel Ludlow. Ludlow had been present when another physician, John Fewster, observed that a dairy farmer who had contracted cow pox did not react to the standard method of small pox variolation. Fewster hypothesized that the cow pox infection had provided immunity to small pox. This idea of cross-immunity from cow pox to small pox was passed on to Jenner by Ludlow. But, it was Jenner who was able to isolate the particular type of the many varieties of cowpox that conferred this immunity. Once identified, Jenner then devised his experiment to prove that vaccination worked. (Others had tried methods similar to Jenner as well. You can read about this history and the relationships between Fewster, Ludlow, Jenner, and others who previously used methods similar to Jenner here.) These key discoveries of Jenner and these other physicians led to the creation modern vaccines.

This takes us to two men, Robert Koch and Louis Pasteur. These men are widely credited with pioneering the germ-theory of disease. This idea stated that illnesses were not the product of noxious air or strange imbalances in the body, but instead were the result of infection from tiny microbes or “germs.” Pasteur used this idea to isolate microbes that caused specific illnesses and used these microbes to develop a host of vaccines that protected recipients from getting sick.

Louis Pasteur

In 1878 Pasteur was working with the bacteria that caused deadly fowl cholera in chickens. Through a series of chance events one set of bacteria was left for days to sit in the hot summer sun. When a lab assistant attempted to induce the deadly fowl cholera disease in chickens with this bacteria, nothing happened. The chickens didn’t die nor did they even become sick. Further, when these same chickens were injected with fresh bacteria, again the chickens did not die or become ill. Combining this observation with his invention of Pasteurization, Pasteur hypothesized that he may be able to induce immunity without harming the chickens by heating, and thereby weakening the bacteria, before injecting it into the chickens. Through a series of experiments Pasteur found that this was indeed the case. Heating the bacteria left it in a weakened state that conferred immunity without harming the recipient.

In addition, Pasteur to creating a fowl cholera vaccine, Pasteur created vaccines for anthrax and rabies in a similar manner.  Shortly after Theobald Smith made a similar discovery – you could create some vaccines by fully killing the bacteria. These discoveries set forth the modern vaccine revolution where scientists were able to find a host of vaccines for viruses and bacteria by using related microbes from other animals that induced cross-immunity without harming the recipient from attenuated (weakened) or killed virus and bacteria.   

However, as we moved steadily into the scientific age with tools to save us from severe illness and death from germs, we came to realize that tools such as vaccines were not enough.  If we failed to adequately and equitably distribute these tools widely in the population, we failed to adequately protect society. We saw this all too clearly with the invention of the polio vaccine and the early failures to distribute it to marginalized populations. Part 4 of this series examines these issues of vaccine equity in the mid-20th century.  

Troy Tassier is a professor of economics at Fordham University and the author of  The Rich Flee and the Poor Take the Bus: How Our Unequal Society Fails Us during Outbreaks.

Part 1: Asia: The Earliest Inoculations

Part 2: Inoculation in the North American colonies and Washington’s mandate

Part 3: A Safer Procedure and the Rise of New Vaccinations

Part 4: Vaccine Inequality and the Case of Polio

Part 5: Measles Vaccines and the Importance of School Mandates Today