[The real philanthropic expedition of the smallpox vaccine: monarchy and modernity in 1803]

Smallpox resulted in the death of 30 % of those who acquired it, so the preventive method discovered by Edward Jenner (London, 1798) spread very quickly. At the request in 1803 of Carlos IV, king of Spain, his government evaluated offers to carry smallpox vaccine to the colonies. The selected proposal, by doctor Francisco Xavier de Balmis, sought to take the lymph to America and Asia in a chain of arm to arm vaccination of foundlings. The Expedition set sail from Corunna on November 30, 1803, stopped in the Canary Isles, Puerto Rico, and Venezuela and after Caracas (1804) split in two groups. Balmis led some members of the Expedition to Cuba and Mexico. For the trip to the Philippines, in 1805, parents lent their children in exchange for economic compensation and the promise that the boys would be returned home. The Expedition returned to Mexico in August, 1807, but Balmis separately took vaccine to China and returned to Spain. Another contingent of the Expedition, under vice-director José Salvany, took vaccine to what we know as Colombia, Ecuador, Peru and Bolivia. His assistant Manuel Grajales reached the Chilean Patagonia in 1811. This article also comments on three principal themes - the institutional management of the scientific project, the conflicts that characterized its course, and the children's experience. The Vaccine Expedition was a brave and humanitarian endeavor, but also an extraordinary sanitary and administrative success. It was not until the twentieth century that a global eradication campaign eliminated smallpox in the world.