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A Concise History of Immunology

The concept of immunity from disease dates back at least to Greece in the 5th century BC. Thucydides wrote of individuals who recovered from the plague, which was raging in Athens at the time. These individuals, who had already contracted the disease, recovered and became “immune” or “exempt.” However, the earliest recognized attempt to intentionally induce immunity to an infectious disease was in the 10th century in China, where smallpox was endemic. The process of “variolation” involved exposing healthy people to material from the lesions caused by the disease, either by putting it under the skin, or, more often, inserting powdered scabs from smallpox pustules into the nose. Variolation was known and practiced frequently in the Ottoman Empire, where it had been introduced by Circassian traders around 1670. Unfortunately, because there was no standardization of the inoculum, the variolation occasionally resulted in death or disfigurement from smallpox, thus limiting its acceptance.