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the story behind the book

A heated year in Boston in the ‘Fever of 1721’

david wilson for the boston globe

In the midst of Boston’s worst smallpox epidemic, the Rev. Cotton Mather tried to get the city’s doctors to try a new idea he had heard from an African slave. The man, named Onesimus by Mather, had told the minister that the scar on his arm came from his African childhood; when smallpox swept through his village, the healthy were protected by a small dose of disease, enough to confer immunity.

In 1721, almost nobody in Boston’s young medical establishment was willing to try out “a procedure that sounded entirely improbable,” said debut author Stephen Coss. It didn’t help, Coss added, that Mather’s reputation had been damaged by his role in the Salem Witch Trials, for which he had never apologized. Already known as a daring physician for performing the first mastectomy in the American colony, Zabdiel Boylston was the only doctor who responded to Mather’s letter promoting inoculation, Coss said. He wrote back to Mather, “and we think he talked to a few of the Africans in Boston to get first-hand accounts.”


And then, on June 26, 1721, he inoculated his own six-year-old son with smallpox. People were outraged, Coss said, and despite the procedure’s success it would be decades before inoculation was fully accepted. (The tide began to turn when George Washington had all his troops inoculated in 1777.)

In “The Fever of 1721,” Coss chronicles one overheated year in Boston’s history. It included not only Boylston’s daring experiment but also the rise of the Boston Caucus, a pre-revolutionary political independence movement, and the founding of “the country’s first truly independent newspaper,” the New-England Courant, which Benjamin Franklin’s older brother, James “started in 1721 specifically to exploit the inoculation controversy.” From journalistic clickbait to medical controversies, Coss observed, “a lot of the issues people faced then, we still face.”


Coss will read 7 p.m. Tuesday at Harvard Book Store.

Kate Tuttle, a writer and editor, can be reached at