On February 12, 1804, at seven in the morning, an eight-year-old girl stood in the living room of Dr. don Tomás Romay. Her arm still throbbed, a slight if persistent hum that seemed to invite her touch. Involuntarily, she reached for the puckered spot, swollen into a great bubble on the soft flesh of her inner arm. The incision was made a week or so before, and news of it spread in Havana as quickly as the smallpox itself. The girl had only just arrived from Puerto Rico the day before. Yet here she was, waiting in the home of this strange man. He would soon pluck open her arm, draining it of the clear liquid the adults curiously coveted. The cut stung, but perhaps satisfyingly so, a welcome release after days of anticipation. The first doctor and the woman who enslaved the girl had prohibited her from rubbing her own skin. The delicate wound must be left to knit itself back together. Each wave aboard the ship threatened a misstep, one that might easily undo the vaccination.
But what had she known of smallpox? Did she understand that she was now protected from this disease for life? What snippets—offered in dulcet persuasions to the woman who owned her—might she have stolen to explain why her body grew such precious fruit? Now, in Cuba, this new doctor thrilled as he harvested her yield, grafting new furrows of it into his two sons. Romay published vignettes of this encounter as an experiment, and readers of the Papel Periódico de La Habana enjoyed a first-hand account of his makeshift medical trial, one he reported as having performed upon his own children. Describing each step in detail, the doctor invited the public to evaluate the efficacy of this new, miraculous technology. 
Having convinced his peers, Romay used the fluid extracted from this one enslaved girl to vaccinate two hundred other children, including the sons and daughters of several prominent plantation owners, such as Manuel O’Farrill, Ignacio Pedroso, and Martin de Arostegui, who through political influence and wealth grew increasingly responsible for the public welfare of the island. These planters volunteered enslaved children from their estates to travel in and between the capital, fashioning a small network of child carriers, their bodies transformed into vessels that might save the island from future disaster. Through the calculus of the piezas de Indias, slaveholders may have valued enslaved children far less than their able-bodied elders, but their young flesh could still be put to work in the service of the Crown. Subtle allusions to these children, whose experiences with the vaccine are otherwise undocumented, suggest the extent to which enslaved peoples encountered experimental medicine beyond the formal purview of medical trials and the Protomedicato, the royal medical tribunal of the Spanish Empire.
From this initial encounter, Romay continued to rely on the slave trade and slavery to learn about, share, and propagate the vaccine. In doing so, he and his allies found ways to intervene in some of the most pressing debates about slavery, the slave trade, and its future—key issues laid before both Cuban and Spanish authorities in the wake of the Haitian Revolution. As anti-colonial and anti-slavery rebellions took root across the Atlantic World, imperial authorities, if they hoped to hold on to their empires, were compelled to address the violence of the slave trade and reform the inhumane treatment of enslaved peoples. Romay leveraged the vaccine, along with his ostensibly humanitarian sentiments, to remake a more “humane” slave trade. In turn, he gained access to and experimented upon enslaved children, carving out additional opportunities for himself as an expert on both vaccination and Black bodies.
The Spanish Crown enthusiastically let him do so, as vaccination became a compelling way for King Carlos IV to maintain the royal paternalism and unfree labor relations that sustained his colonial rule. In the sixteenth and seventeenth centuries, Spain affirmed its obligation to enslave Africans through claims to spiritual salvation. By the eighteenth and nineteenth centuries, this claim now extended to the corporeal realm. Remaking their role as caretaker, royal authorities now turned to medicine to hold abolitionist fervor at bay and legitimize their authority over Africans they deemed in need.
For example, in 1811, Romay remitted a sharp rebuke to the Cuban Consulado after inspecting the Consejero, a Spanish brigantine that had lost a fourth of its human cargo to smallpox en route from Loango (present day Gabon and the Congo Republic). As he implored:
What acclaimed advantages do the unfortunate gain with slavery, if they are scarcely torn from their homes, when they are buried in the abyss of the sea? Is it no worse to live, though wandering between the forests, without home, without property, without laws, nor religion, than to die at the hands of the unpunished will of a few men, who do not recognize a right other than that of their own sordid interest?
To drive his point home, he invoked the abolitionists Agustín Argüelles, a Spanish minister, and José Miguel Guridi Alcocer, a deputy from Tlaxcala, Mexico, who had called on Spain to immediately end the transatlantic slave trade months earlier that year.
With how much vehemence and justice would not Mr. Argüelles and Mr. Alcocer declaim against this barbaric trade, if they understood such abhorrent facts? The conservation of agriculture on this island, the prosperity of a few, they would ask, is this more preferable than the life of just one man?
Romay did not share their abolitionist views—indeed, he would later collaborate with the Bishop of Havana to suppress the uprisings known as the Aponte Rebellion—but he did use their arguments to try and secure a new slave code that would regulate the care and treatment of slaves on board slave ships (and boost the professional opportunities for licensed medical doctors in the empire).
As the doctor opined, “although many ships leaving our ports for those of Africa do not carry the kind of cargo that requires a surgeon,” that is, exported goods, they inevitably would return, transporting “not bales nor bundles” but hundreds of human beings. Ship captains, he wrote, “know very well that these are men, although blacks and slaves, [and] they must provide them with all the aid demanded by Humanity and ordered by our laws.” Despite his overtures, neither Spain nor Cuba issued a new code, and slave health remained a priority for authorities only when it appeared to threaten the social, political, and economic order, as it did when slave ships introduced the threat of a smallpox outbreak.
The vaccine, in addition to providing a humanitarian argument against the abolition of the slave trade, made it safe for Atlantic societies to traffic in slaves without the recurring risk of an epidemic. As Romay once explained, “it is [Africans] that regularly introduce the epidemics of smallpox, [and] they need with great urgency to be preserved with the vaccine and contribute to its conservation.” Through this logic, Romay secured for himself a perpetual supply of bodies to reproduce and conserve the vaccine, casting the enslaved at once as contaminant and remedy—one that only state medical authorities could manage. Each body vaccinated was an opportunity to learn about the vaccine, its fragilities, and secure means to ensure its preservation—knowledge that helped doctors further the colonial project.
Many of these encounters unfolded off the record. Though authorities sought to make a spectacle of vaccination—and draw in parents who remained skeptical of this new technology—most operations did not garner a wide audience. Instead, doctors vaccinated quickly and quietly in private homes, makeshift clinics, and slave baracoons, leaving very little documentary evidence (beyond numerical logs) about the events taking place inside. In this way, the archival apparatus documenting the history of the vaccine helped sustain the erasure of enslaved children and the systemic violence that offered doctors access to them and the immunizing fluid their bodies produced on behalf of the state.
Scientific literature sustained a similar erasure. Despite the role of enslaved children in preserving, reproducing, and enabling new knowledges about the vaccine, vaccination in guides and pamphlets remained figured through descriptions and images of white, European children. We see this most prominently in Origen y Descubrimiento de la Vacuna, a guide published in the Mexican government newsletter, Gazeta de Mexico, a few months after doctors established the vaccine in Mexico City in 1804. Translated from French by Spanish minister Dr. Pedro Hernandez and originally published in Madrid, the guide was reprinted a few years later in both Mexico City and Bogotá, Colombia.
Seemingly the first vaccination guide published in the Americas, the Hernandez tract taught practitioners how to vaccinate patients by recognizing the progression of the vaccine, as demonstrated in the engraving below. Instructions in the text are coded in visual cues that assume a white body, indicating progress through pinked skin. In addition to practical instruction, the guide offered proof of the vaccine’s safety by laying claim to tests and trials conducted in Europe, in which physicians in the acclaimed halls of Paris and London had affirmed its efficacy. As the primary means of instructing doctors in the Spanish Americas, the guide and the child depicted within it elided the numerous trials and exchanges conducted upon enslaved children by doctors like Romay. With the vaccine, colonial officials hoped to eradicate both disease and evidence of the violence of slavery. Following the enslaved children who incubated and reproduced the vaccine makes visible this failed eradication.
Farren Yero is a postdoctoral associate in Gender, Sexuality, and Feminist Studies at Duke University, where she obtained her Ph.D in History. Her current book project, Atlantic Antidote: Race, Gender, and the Birth of the First Vaccine, is a history of vaccination and family politics in the age of revolution. Her writing has appeared in The Recipes Project and The Panorama and her research has been supported by the ACLS, Fulbright-Hays, the Andrew W. Mellon Foundation, the John Carter Brown Library, and the Newberry Library. You can find her on Twitter: @feyero.
Title image: Engraving of a vaccinated child. Gazeta de México No. 13. May 26, 1804. Courtesy of the Biblioteca Nacional de España.
Childs, Matt. The 1812 Aponte Rebellion in Cuba and the Struggle against Atlantic Slavery, Chapel Hill: The University of North Carolina Press, 2009.
Ferrer, Ada. Freedom’s Mirror: Cuba and Haiti in the Age of Revolution, New York: Cambridge University Press, 2014.
Few, Martha. For All of Humanity Mesoamerican and Colonial Medicine in Enlightenment Guatemala. Tucson: The University of Arizona Press, 2015.
Johnson, Antoine S. Elise A. Mitchell, and Ayah Nuriddin, “Syllabus: A History of Anti-Black Racism in Medicine,” Black Perspectives (August 12, 2020).
López Denis, Adrián. “Disease and Society in Colonial Cuba, 1790-1840,” PhD Disseration, University of California, Los Angeles, 2007.
Niklas Thode Jensen, “Safeguarding Slaves: Smallpox, Vaccination, and Governmental Health Policies among the Enslaved Population in the Danish West Indies, 1803–1848,” Bulletin of the History of Medicine 83, no. 1 (March 27, 2009): 95–124.
Ramírez, Paul F. Enlightened Immunity: Mexico’s Experiments with Disease Prevention in the Age of Reason, Stanford: Stanford University Press, 2019.
Rigau-Perez, Jose G. “The Introduction of Smallpox Vaccine in 1803 and the Adoption of Immunization as a Government Function in Puerto Rico.” The Hispanic American Historical Review 69, no. 3 (August 1989): 393-423.
Warren, Adam. Medicine and Politics in Colonial Peru Population Growth and the Bourbon Reforms. Pittsburgh: University of Pittsburgh Press, 2010.
Weaver, Karol. Medical Revolutionaries: The Enslaved Healers of Eighteenth-Century Saint Domingue. University of Illinois Press, 2006.
 Tomás Romay, Memoria sobre la introducción y progresos de la Vacuna en la isla de Cuba (Havana, 1805).
 For more on childhood, slavery, and colonialism in the Iberian World, see: Raising an Empire: Children in Early Modern Iberia and Colonial Latin America, eds. Ondina E. González and Bianca Premo (Albuquerque: University of New Mexico Press, 2007).
 Stefanie Hunt-Kennedy takes up a similar set of politics to analyze the relationship between British abolitionism, amelioration reforms, and disability, pointedly arguing that the humanitarian idea of citizenship that abolitionists offered to the enslaved was a “crippled” form of citizenship. On this, see Between Fitness and Death Disability and Slavery in the Caribbean (Urbana: University of Illinois Press, 2020).
 Archivo Nacional de la República de Cuba (ANC), Real Consulado Junta de Fomento, Leg. 150, No. 7409. f. 5-8. Romay to the Consulado. Havana. July 12, 1811.
 Archivo General de Indias, Papeles de Cuba, Leg. 1815, Juan Joseph, Bishop of Havana to Juan Ortiz de Apodaca, Presidente del Real Audiencia y Gob. y Capn General. April 17, 1812.
 ANC, Real Consulado Junta de Fomento, Leg. 150, No. 7409. f. 5-8. Romay to the Consulado. Havana. July 12, 1811.
 Romay, Memoria, p. 22.
 Gazeta de Mexico. Suplemento. No. 13. May 26, 1804.