On a Sunday morning in 1805, Father Andrés Rosillo y Meruélo preached about a marvelous new discovery—a vaccine that promised to save his parishioners and their families from disease. The priest proclaimed in his sermon that day that Christ’s sacrifice on the cross not only enabled man’s eternal salvation but also freed him from the scourge of smallpox. Redemption from this plague came in the form of a vaccine, discovered just a few years before, and transported to the Spanish Americas in 1804. But this gift came with strings attached. Rosillo insisted that the vaccine be received fearfully and willingly, as a reminder to Church acolytes of their duties to God. Indeed, as a divine gift, remitted by King Carlos IV, vaccination was ostensibly both free and voluntary, requiring the consent of patients or parents throughout the Spanish Empire. In a moment increasingly identified by secularization and professionalization of medical science, this paper addresses the central role of parish priests in navigating the question of medical consent. Drawn from sermons, medical records, and colonial correspondence, I analyze an episode of epidemic outbreak and vaccine use to address key questions about the work of religion in Mexico at the intersection of state intervention, medical practice, and patient care.
