Abstract
In the late 1930s, the 17D vaccine against yellow fever was produced in record time. 17D was and is an excellent vaccine. Its rapid diffusion led, however, to several problems, the most important among them being the 1942 massive contamination of the vaccine distributed to the US Army by the hepatitis B virus. The US part of this story is relatively well-known, but its Brazilian part much less so. In 1940, scientists who were producing the 17D vaccine in Rio de Janeiro found that it was contaminated by an "icterus virus" that originated in normal human serum. They solved this problem through the exclusion of human serum from vaccine production, but failed to persuade their US colleagues to do the same. The Rio experts, aware of the potential pitfalls of a new technology, carefully supervised the consequences of their vaccination campaigns. They were thus able to rapidly spot problems and eliminate them. By contrast, US scientists, persuaded of their technical superiority and distrustful of warnings that originated from a "less developed" country, neglected to implement basic public health rules. A major disaster followed. (Am J Public Health. 2021;111(9): 1654-1660. https://doi.org/10.2105/AJPH.2021.306313).