How Was Vaccination Developed?

The first evidenced attempts to bring about immunity deliberately were carried out by the Chinese and the Turks in the fifteenth century. A range of reports suggest that the dried crusts obtained from smallpox pustules were either inserted into small cuts in the skin (a technique called variolation) or inhaled into the nostrils.

In 1718, Lady Mary Wortley Montagu observed the constructive effects of variolation on the local population and had the technique performed on her own children. The process was considerably improved by an English physician Edward Jenner, in 1798.

Contribution of Edward Jenner:
Impressed by the fact that milkmaids who were earlier in contact with the mild form of cowpox were subsequently invulnerable to smallpox, which is a disfiguring and often lethal disease. Jenner elucidated that introduction of fluid from a cowpox pustule into people (i.e., inoculating them) might guard them from smallpox. To investigate this idea, he vaccinated an eight-year-old boy with liquid from a cowpox pustule and later purposely infected the child with smallpox. As predicted, the child did not develop smallpox disease.

Jenner’s technique of immunizing people with cowpox germs to guard against smallpox disease, spread speedily throughout Europe. However, for many reasons, including a lack of palpable disease targets and information about their causes, it was almost a hundred years before this technique was functional for other diseases.

Further advances by Louis Pasteur:
As so often happens in the field of science, serendipity in amalgamation with perceptive observation led to the next chief advance in immunology—the induction of immunity to cholera.

Louis Pasteur had successful accomplishments in growing the bacterium thought to cause fowl cholera in pure culture and then later had shown that chickens that were injected with the cultured bacterium developed cholera. Then fate intervened when, on returning from a summer vacation, some chickens he had injected with an old culture became ill, but, to Pasteur’s surprise, they recovered from the disease. Pasteur then grew a fresh culture of the bacterium with the purpose of injecting it into some fresh chickens. But, as the legend goes, his supply of chickens was inadequate, and therefore he used the already injected chickens. Again to his surprise, the chickens were totally protected from the disease.

Pasteur hypothesized and established the fact that ageing had weakened the virulence of the pathogenic bacterium and that such a weakened strain might be injected to defend against the disease. He called this weakened strain a vaccine (from the Latin vacca, meaning “cow”), in admiration of Jenner’s work with cowpox inoculation, Pasteur extended his successful findings to other diseases, demonstrating that it was possible to attenuate a pathogen and later administer the attenuated strain as a vaccine.

Pasteur first vaccinated a group of sheep with heat-killed anthrax bacillus (Bacillus anthracis) in a classic experiment at Pouilly-le-Fort in 1881; he then confronted the vaccinated sheep and a few unvaccinated sheep with a virulent culture of the bacillus. As a result, all of the vaccinated sheep remained alive, and all the unvaccinated animals died because of the disease. These experiments marked the beginnings of the discipline of immunology.

Pasteur later in 1885 administered his first human vaccine to a young boy who had been bitten by a rabid dog. The boy, Joseph Meister, was vaccinated with a series of attenuated rabies virus preparations. The boy survived. Pasteur’s fame spread, and people from all over Europe rushed to Paris to get treatment for rabies.

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