[Producing an immunizing agent: images from the production of a yellow fever vaccine].

Through analysis of a set of photographs on the production of a yellow fever vaccine in Brazil, the article discusses the use of images as a research source in the history of medicine and public health. part of a historical archive belonging to the Fundação Rockefeller, stored at the Casa de Oswaldo Cruz/Fiocruz the photographs were produced between the 1930s and 1940s by the Fundação Rockefeller and Brazil's National Yellow Fever Service, institutions then responsible for research and control of the disease in Brazil. The article raises some questions generally posed by those who employ images as sources or objects of interpretation in the production of historical knowledge, and also points to the theoretical, conceptual, and methodological aspects involved in this process of analyzing images. It goes on to interpret these photographs from the beginning of the yellow fever vaccine.