Black History and the Early History of Inoculation in America

This is the story of Onesimus, an African slave, who is responsible for the first major medical advancement in American history: Inoculation against smallpox.

Up until the later half of the 1700s, smallpox outbreaks were a major threat to public health in the American Colonies. Smallpox virus droplets from an infected individual (usually from speaking) enter the respiratory tract then into the bloodstream, and in turn create pustules in the skin. Some smallpox strains have mortality rates of 30%. Smallpox can also cause permanent scarring and blindness. In 1721, in Boston MA, a major smallpox outbreak claimed about 14% of lives in the colony and over half the population was infected.

In this largely pre-scientific era for medicine, physicians and amateur scientists tried all measure of nostrums and tinctures to cure the disease. Cotton Mather, a puritan preacher and amateur scientist, was no exception. Unlike his peers, however, Mather did something unusual for the time. As early as 1716–before the Boston outbreak–he had consulted his African slave Onesimus for advice on how to treat smallpox.

The reigning ‘scientific’ view of race at the time was that of racialism–the idea that Africans are an intrinsically inferior race to white Europeans. Turning to a purportedly intellectually inferior race for knowledge was contrary to the prevailing view and–as we will see shortly–contributed to an uproar.

So, why did Mather bother consulting with Onesimus?

At the time it was known that people who had been infected with smallpox would be less likely to get it again, and if they did, they experienced it much more mildly. Slave dealers often advertised that their slaves had survived smallpox. Mather asked Onesimus whether had had smallpox. Mather recorded Onesimus’ reply:

He answered both Yes and No; and then told me that he had undergone an operation which had given him something of the smallpox and would forever preserve him from it; adding that it was often used among the Guaramantese and whoever had the courage to use it, was forever free from the fear of contagion.


Mather interviewed other African slaves around Boston about this operation. They all described and explained inoculation–the practice of introducing virally infected material into the skin via a scratch. In fact, many non-Western cultures had long ago discovered some form of inoculation for addressing smallpox. As early as 1000 BC, the Chinese would introduce pus from a smallpox pustule into a scratch in the skin or the mucus membrane of the nose, or blow scabs from pustules into the nose. In India, there were similar techniques. West Africa was no different.

Mather called for a mass inoculation of the Boston public. He sent letters out to the leading scientists and doctors in the colony. Only the physician Zabdiel Boylston embraced it after successfully testing it on several hundred his slaves and, later, his own son.

Boston’s other leading scientists and physicians, however, all rejected Mather’s proposal and promptly created an anti-inoculation league:

Many of the town’s people were against inoculation, including members of Mather’s congregation. All the physicians in town except Boylston were opposed to his
crusade. They were led by the only physician in Boston with the MD degree, Dr William Douglass. John Checkley, an apothecary who had a personal feud with Mather, and Douglass formed the Society of Physicians Anti-Inoculators which met regularly in coffee houses to denounce inoculators. The July 17–24 edition of the Boston News-Letter published an article by Dr William Douglass that attacked Boylston for performing inoculations. On 7 August James and Benjamin Franklin [yes, that Benjamin Franklin] published additional attacks in their newspaper, the New England Courant.


The prevalence of ‘scientific’ racialism in part motivated the knee-jerk rejection of inoculation. It’s otherwise difficult to explain why resistance persisted despite the evidence. In what is, by some historians, considered to be the first controlled clinical trial, Mather and Boylston reported in early 1722 that 2% of 287 inoculated patients died compared with 842 deaths among the 4917 infected in the natural way (14.9%). Yet, despite the experiments, the anti-inoculators persisted.

In the press, doctors condemned inoculation because it was “the laughable, unchristian product of occult African practices” (quoted from Washington, 2010, p. 72). Resistance even became violent: Someone (unsuccessfully) firebombed Mather’s house and left an accompanying note:

Cotton Mather, You Dog, Dam You: I’ll inoculate you with this, with a pox to you.

Until recently–and still in most accounts–Cotton Mather is credited with discovering inoculation and being the first significant figure in American medicine. But now we can give credit where credit is due: The life-saving medical practice of inoculation came to America from West African communal knowledge via Onesimus.

Lessons and Insights

Lesson 1: Inoculation is an all-natural preventative modality against infectious disease that is safer than the disease it prevents. After the clinical trial data came out, the anti-inoculators persisted nevertheless because they failed to reason well and were overconfident in their own knowledge. While it’s true that inoculation isn’t perfectly safe, it is much more safe than getting smallpox ‘naturally.’ So, among other errors, anti-inoculators failed to assess risk as a comparative measure and instead evaluated it as an absolute measure. Today, the descendants of anti-inoculators (opponents to vaccines) continue this tradition of flawed reasoning. Vaccines are not risk free but their risks are orders of magnitude less than the risks posed by natural infection.

Lesson 2: Inoculation is a natural way of creating immunity without the risk of natural full exposure. If you like the principle and benefits of inoculation, you’re gonna love vaccines! You get immunity and it’s even safer than inoculation!

Not Lessons:

Not Lesson 1: It’s tempting to infer the lesson that since ancient medical wisdom, in this case, held the key to saving us from a perennial health problem that we should turn to ancient medical practices for current health problems. Ancient practices also include a long list of medically ineffective and harmful practices. For example, blood-letting, drinking liquid mercury, eating animal tusks, applying python bile to treat genital ulcers, morphine to cure children’s coughs, arsenic are all ancient remedies no sane person would promote today.

The fact that a treatment has been developed and practiced for centuries by a community is a reason to consider it for testing. But from the mere fact alone that a practice has ancient roots, it does not follow that it is safe and effective. That can only be known through controlled trials.

Not Lesson 2: Another mistaken lesson people might infer is that experts are unreliable sources of knowledge. It’s a common contrarian tactic to point to historical instances where the experts where wrong and a lone intrepid Truth Warrior had to fight them. People who deploy this argument inevitably imagine themselves to be among the Truth Warriors. There are a few problems with this familiar line of argument (it’s so common it has its own name: The Galileo Gambit).

The first problem has to do with the specifics of the case. At least before the clinical trial, it wasn’t unreasonable to at least withhold judgement on inoculation. The idea of smearing puss from infected individuals into the open wounds of healthy people should give anyone pause. But as I mentioned previously, knowing that a treatment has been long practiced by a culture gives us reason to investigate it. The mistake was to dismiss the practice outright which was in part–but not entirely–a product of the prevailing racial attitudes.

As I mentioned, those who deploy this argument typically imagine themselves to be Galileos. But they fail to consider that for every Galileo in history there were hundreds of thousands of people who were completely wrong. Just cruise the comments section of any online science article! Given the relative probabilities, which is such a person more likely to be?

There’s a lot more to say about this line of argument but I’ll end with this. We must distinguish between a consensus of pre-scientific or early scientific experts and a consensus of experts in a mature science today. You cannot compare the state of medical knowledge and science of the early 1700s to now. To do so would be willfully naive.

So, while it’s true that there are historical cases when a consensus of experts turned out to be wrong, you can’t appeal to pre-scientific eras as evidence against a consensus of experts in a mature science. And while it’s true that a consensus of experts in a mature science can sometimes be wrong, usually they are right. And the likelihood is vanishingly small that a non-expert with little to no training in a field somehow stubbled upon evidence that the experts did not take into account. If an expert consensus changes, it’s usually because experts within that field have discovered new and better evidence.

To paraphrase Plato: You get your accounting done by people who have studied accounting because you understand that they know more than you about accounting. You get your car repairs done by people who have studied auto mechanics because you understand that they know more than you about auto mechanics. You go to court with people who have studied the law because you understand that they know more than you about the law. The same goes for scientific experts. People who study something for many years know more about that thing than do people who don’t.

Yes, it’s true that sometimes experts will be wrong but they are less likely to make mistakes in their domain of knowledge than are you. And if the vast majority of them agree, the wise person defers to the agreement of experts.

Final Note: Benjamin Franklin eventually became an advocate for inoculation, especially after his own son died of smallpox.


  1. Best, M. 2004. “‘Cotton Mather, You Dog, Dam You! I’l Inoculate You with This; with a Pox to You’: Smallpox Inoculation, Boston, 1721.” Quality and Safety in Health Care 13 (1): 82–83.
  2. Niederhuber, Matthew. 2018. “Science in the News.” Science in the News. October 30, 2018.
  3. Washington, Harriet A. 2010. Medical Apartheid the Dark History of Medical Experimentation on Black Americans from Colonial Times to the Present. Paw Prints.

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