The History of the First Vaccine

Smallpox had been a deadly disease since the earliest recorded history. It spread through every major migration, from the Crusades to the founding of the Americas, and devastated populations wherever it went. The case-fatality rate was 20 – 60% among adults. For infants in the late 1800s, the fatality rate approached 80% in London and 98% in Berlin. By comparison, the flu, which is still considered a very serious disease, kills far less than 1% of those infected. What’s more, smallpox left most survivors with disfiguring scars, and up to a third of those it infected were blinded.

Survivors were well known to be immune. As early as the 400s BC, they were called upon to treat the sick. This knowledge led to people in Africa, India, and China deliberately infecting people with mild forms of smallpox. They hoped to prevent infection with more deadly forms and provide life-long protection. The practice was introduced in Europe in the 18th century. This was known as inoculation or variolation. The fatality rate of those inoculated was just 2 – 3%, which led to widespread use of inoculation by European royalty and common people alike.

“In 1757, an 8-year-old boy was inoculated with smallpox in Gloucester; he was one of thousands of children inoculated that year in England,” wrote Stefan Riedel, MD, PhD, in a paper for NCBI. “The procedure was effective, as the boy developed a mild case of smallpox and was subsequently immune to the disease. His name was Edward Jenner.”

In 1798, after having become a physician, Jenner published his long-term observation that milkmaids—who were often afflicted with cowpox, a milder disease that had some characteristics in common with smallpox —seemed immune to smallpox. To see if this protection could be artificially induced, he exposed a "healthy boy" to cowpox virus from a milkmaid, and then attempted to infect the boy with smallpox. (This experimental method would be prohibited today on ethical grounds.) It worked. We now know that the two diseases shared antigens, disease-fighting proteins produced by the immune system. The cowpox prepared the boy’s immune system, so he could fight smallpox.

With this discovery, the first vaccine had arrived. The word vaccine, in fact, comes from the Latin word for cow, “vacca.” The technique of vaccination against smallpox spread quickly throughout the world. In 1980, the World Health Assembly officially declared "the world and its peoples" free from endemic smallpox.

In the years since, scientists have made great progress in developing vaccinations for many diseases. Cases of the measles, for instance, dropped from 894,000 in 1941 to 500 cases in 1996 thanks to a vaccine.  The ways of achieving resistance have grown, as well. All of the methods are being used in projects to develop a COVID vaccine. We hope we have as much success as Dr. Jenner did.

Marie George, MD, FIDSA, is an infectious disease specialist with SVMC Infectious Disease.