[Cecily]

The operation Onesimus referred to consisted of rubbing pus from an infected person into an open wound on the arm. Once the infected material was introduced into the body, the person who underwent the procedure was inoculated against smallpox. It wasn’t a vaccination, which involves exposure to a less dangerous virus to provoke immunity. But it did activate the recipient’s immune response and protected against the disease most of the time.

Mather was fascinated. He verified Onesimus’ story with that of other enslaved people, and learned that the practice had been used in Turkey and China. He became an evangelist for inoculation—also known as variolation—and spread the word throughout Massachusetts and elsewhere in the hopes it would help prevent smallpox.

But Mather hadn’t bargained on how unpopular the idea would be. The same prejudices that caused him to distrust his servant made other white colonists reluctant to undergo a medical procedure developed by or for Black people. Mather “was vilified,” historian Ted Widmer told WGBH. “A local newspaper, called The New England Courant, ridiculed him. An explosive device was thrown through his windows with an angry note. There was an ugly racial element to the anger.” Religion also contributed: Other preachers argued that it was against God’s will to expose his creatures to dangerous diseases.

https://www.history.com/news/smallpo...-cotton-mather