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Year: 1716​

Who: “Onesimus,” enslaved by Puritan minister Cotton Mather​

Where: Boston, Massachusetts ​

What: Onesimus, an enslaved African man in 18th-century Boston, made a monumental contribution to public health through his knowledge of smallpox inoculation. In 1721, when Boston was ravaged by a smallpox epidemic, Onesimus shared with his enslaver, Cotton Mather, a technique practiced in West Africa: exposing healthy individuals to small amounts of material from smallpox sores to confer immunity. This method, called variolation, was novel to the colonists but proved critical in mitigating the epidemic. Mather advocated for variolation based on Onesimus' account, leading to its successful implementation by physician Zabdiel Boylston despite widespread skepticism and opposition.

Born in West Africa, likely among the Akan people, Onesimus was captured and sold into slavery, eventually becoming part of Mather’s household in 1706. His African origins meant that he was already familiar with inoculation practices, a traditional method used in his community. Through his cultural knowledge, Onesimus directly influenced the early adoption of inoculation in North America, saving countless lives and laying groundwork for modern vaccination.

Historical records, primarily Mather’s biased writings, suggest that Onesimus was intelligent, pragmatic, and assertive. He retained his Puritan name after gaining partial freedom, possibly for practicality. While remembered for introducing inoculation to colonial America, Onesimus' life embodies a story of survival, innovation, and resistance within the harsh realities of slavery. His legacy as a pioneer in public health is only part of his remarkable and multifaceted life.

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