[Between vaccines, diseases, and resistances: the impacts of a smallpox epidemic in nineteenth-century Porto Alegre].

This article examines a smallpox epidemic which killed 1% of the population of Porto Alegre in 1874. Through extensive documentary research and comparison with data from those who died, we problematize why smallpox manifested as an epidemic in the city. Maps showing vaccination in the years preceding the outbreak reveal that only low levels of the population of Porto Alegre participated in prevention efforts, and the benefits of these efforts were ignored by the different social groups which were interconnected within the city. As sick soldiers arrived from other places, the disease spread rapidly through the city and caused the death of hundreds of people.