[La expedición Balmis en el Suplemento a la Gazeta de Madrid (14 de octubre de 1806), difusión hispana.]

The Madrid Gazette published a Supplement on October 14, 1806, regarding the arrival of the Director of the Royal Expedition Vaccine Philanthropy, Francisco Xavier Balmis, and the reception held by King Carlos IV. Balmis had completed his journey across the Spanish overseas territories, taking the vaccine against smallpox from arm to arm with the help of a human chain of children. During this journey, Balmis also established Vaccination Boards and endeavoured to identify cows with cowpox. The publication endorsed the policies of a declining Bourbon monarchy and marked the peak of Balmis' professional career. Both sides emerged victorious: the Crown showcased itself as the sponsor and organiser of this altruistic journey, in line with prior scientific expeditions; and Balmis secured his place in Public Health history as the director of the first international vaccination campaign. This did not mean the culmination of the expedition, as other members were still administering vaccinations in the Philippines and South America. The main objective of this study was to assess the importance of the newspaper Madrid Gazette, outline the contents of the publication, authenticate the origins of the documentary sources underpinning its composition, and confirm its impact and citations throughout 19th-century Spanish publications. The components of the publication, its origins, as well as Balmis' involvement in its creation, have been substantiated. The Supplement's importance is defined by its utility as a resource for commemorating and appreciating the expedition.