The development of vaccination is one of the (relatively) rare cases in medical history of our ancient ancestors getting the right idea right away. And while actual vaccine research started in the 18th century, its roots can be traced as far as eight centuries prior, to the practice commonly known as inoculation.

It all started with smallpox. In an earlier section of our exhibition, we have presented the key facts about smallpox, a deadly viral disease that is now considered eliminated. Its symptoms begin with fatigue and fever, followed by a characteristic skin rash. However, smallpox can also cause bronchitis, pneumonia, and blood poisoning. These complications led to the 30% fatality rate among infected people.

We know that smallpox had existed at least as far back as 1500BC. The earliest known victim of smallpox was the Egyptian pharaoh Ramses V. He died in 1145BC, and mummification preserved his skin covered in tell-tale lesions. The surviving written records suggest that the Ancient Greeks were also familiar with the disease. Furthermore, they already knew that you could only get smallpox once. In the 21st century, we know that the reason behind that was the immunity to the virus that develops in people who recover from it.

However, it took almost two thousand more years for us to see the first deliberate attempt at smallpox prevention. Exact timing is still debated, but the practice of inoculation was described for the first time in 1643 in China. (Nowadays, when specifically referring to inoculating someone with smallpox, we use the term variolation, derived from the scientific name for its two strains - Variola major and Variola minor.)

Inoculation process involves transferring a small bit of organic material (usually dried scabs in case of smallpox) from a mildly infected person to a healthy person to introduce their immune system to the disease and create immunity. At first, the main goal of inoculation practices was creating immunity in children, as they were considered most likely to die after contracting the disease. The most common method of “implanting these sprouts” was crushing the scabs into powder and putting it up one’s nostril. Alternatively, you could cut off a pustule from a sick child, then make a small cut on a healthy child’s arm and leave the pustule in it for a while.

Different methods of variolation were also used around the same time in Ethiopia, India, West Africa and other locations. Unlike vaccination, this process introduced a “living” virus into a healthy body. In lucky cases, the recipient would be infected with Variola Minor, which was significantly less dangerous but still provided immunity from both variations of the virus. It was not ideal - but it worked well enough when there were no other options.

The first person to introduce the practice of inoculation in Western Europe was Lady Mary Wortley Montagu (1689-1762). She was the wife of a British ambassador in the Ottoman Empire (present day Turkey) and became familiar with the practice while traveling with her husband. She then returned to Great Britain and, after some convincing, was able to have a physician inoculate her children. The procedure was successful, and Montagu’s high social status gave this new and extremely unusual practice some credibility. This, in turn, allowed for it to spread, first in England and then in the rest of Europe. But not before the British government tested it on several prisoners in exchange for freedom, of course.

The next major step in the history of vaccination was made in 1796 by an English country doctor Edward Jenner. Most of Jenner’s patients were local farmers, and he noticed that those among them who worked with livestock and contracted cowpox at one point of their life were immune to smallpox. It was especially common among milkmaids.

Jenner studied this phenomenon and had his research published. Initially, Jenner took some organic material from a milkmaid infected with cowpox and applied it to a cut on the arm of an eight year old boy - just like you would during variolation. The boy got mildly sick but got better six weeks later. Then Jenner repeatedly tried variolating the boy with smallpox and, just as he expected, the boy did not get sick. It turned out that the virus causing cowpox was closely related to the Variola virus. However, cowpox is much milder and less infectious than smallpox and, therefore, inoculating with cowpox became a new, more effective alternative to variolation. Jenner came up with the term “vaccination” to describe the procedure, and later the word came to mean any kind of immunization.

There was, however, a serious flaw in early immunization techniques. If the person or an animal that “provided” the vaccine material was simultaneously carrying another disease, the vaccine would pass it to the recipient together with the cowpox virus. The biggest concern was syphilis. Moreover, many physicians who, at the time, still practiced variolation lost their practice to Jenner’s followers, and tried to discredit his discovery in whatever way they could. They claimed that vaccines were unhygienic and unsuitable for humans, since cowpox originated in an animal. For them, blowing someone else’s scabs up your nose was supposedly more appealing.

Since then, the smallpox vaccine has been altered many times to make it safer and more effective, and immunizations became the most reliable way to prevent a lot of viral diseases. And thanks to the worldwide efforts to contain it through mandatory vaccinations, smallpox was completely eradicated in the wild. The eradication of smallpox serves as the greatest attestation to the effectiveness of vaccines.

On herd immunity

Despite the fact that vaccines have been proven to work for most people, exceptions do exist. Every vaccine has different components, and just like with foods we consume, some individuals can be allergic to those components. So before getting your vaccinations done, you might want to mention any of your known allergies to your physician. Many vaccines are age-restricted because children under certain ages and elderly people tend to have weaker immune systems that cannot resist even the “inactive” version of a virus. That is also the case for immunocompromised individuals suffering from chronic illnesses.

Because of their inability to get immunized, these people are extremely vulnerable to viral diseases, and they have to rely on herd immunity to protect them from encountering such diseases in the wild.

The CDC defines herd (or community) immunity as “a situation in which a sufficient proportion of a population is immune to an infectious disease (through vaccination and/or prior illness) to make its spread from person to person unlikely.” In this situation even individuals that cannot get vaccinated are offered some protection because the disease has little opportunity to spread within their community.

However, when fewer people get vaccinated because of personal decisions or the lack of access to vaccinations, they not only expose themselves to the risk of infection, but make it easier for other non-vaccinated people to catch the disease. That is why herd immunity is extremely important to maintain.

References

Chung, Eun Hee. "Vaccine Allergies." Clinical and Experimental Vaccine Research, Vol. 3, No. 1 (January 2014): 50–57.

McElroy, Dr. Sydnee and McElroy, Justin. "Vaccines." Sawbones: A Marital Tour of Misguided Medicine, episode 49, July 8, 2014.

Montagu, Lady Mary Wortley. "Smallpox Vaccination in Turkey." Internet History Sourcebooks Project.

Shchelkunov Sergei. "Emergence and Reemergence of Smallpox: The Need for Development of a New Generation Smallpox Vaccine." Vaccine, vol. 29 Suppl 4 (2011): D49-53.

"Vaccination." Wikipedia.com.

"Vaccines and Immunizations: Basics and Common Questions." CDC.gov.