Benjamin Colman's 1721 Smallpox Pamphlet and Early Mortality Data

In 1721 Boston, a small pamphlet by minister Benjamin Colman did something unusually durable: it counted. In the middle of a fierce argument over smallpox inoculation, Colman printed figures on who had been inoculated, who had caught smallpox naturally, and how many died in each group.

That matters because the inoculation debate was not just moral, religious, or political. It was also about risk. People wanted to know whether deliberately giving someone a mild form of smallpox was safer than waiting for the disease to spread on its own. Colman’s pamphlet tried to answer that with numbers, not just opinion.

Boston Smallpox Inoculation Data

The basic comparison was simple enough for a modern reader to recognize. On one side were people who underwent inoculation during the 1721 outbreak in Boston. On the other were people who contracted smallpox naturally. The reported death rate among the inoculated was much lower than among those infected in the ordinary way. The figures were not gathered by modern methods, and they should not be treated as exact in the way a present-day public health study might be. Even so, they are usable evidence from the time, and that is rare.

The example most often discussed comes from the Boston epidemic itself, when inoculation was promoted by Cotton Mather and physician Zabdiel Boylston and fiercely opposed by others in the town. Colman, who supported inoculation, helped circulate outcome data during the controversy. His publication did not end the argument, but it changed the terms of it. Instead of trading only fears and accusations, supporters could point to a rough mortality comparison drawn from local experience.

Benjamin Colman’s Pamphlet Legacy

That is why historians of medicine and modern epidemiologists still return to this pamphlet. Not because it was perfect, and not because everyone accepted it, but because it preserved one of the earliest practical attempts in British North America to compare death outcomes between two paths: inoculation and natural infection. It turned a public quarrel into something closer to an evidence-based dispute, even if the evidence was incomplete.

The concrete legacy is surprisingly clear. A pamphlet printed in Boston in 1721 still gives researchers numbers they can examine today, letting them estimate how much safer inoculation appeared during that outbreak than facing smallpox unprotected.

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