Abstract: In the 19th century, when vaccine production and storage technologies were not yet developed, the “arm-to-arm method” made cowpox vaccination possible. That constitutes the important foundation for the elimination of smallpox in developed worlds. However, this is often overlooked by medical historians. By reviewing the characteristics of the smallpox virus and the process by which Edward Jenner “invented” cowpox, this study clarifies the motivation for his work and the historical context in which the “arm-to-arm method” was introduced in England. In contrast, the United States, also utilizing the “arm-to-arm method”, relied on its established postal infrastructure to mail cowpox vaccines and instructions, and to collect pox scabs, effectively solving the problem of vaccine production and distribution. Learning from history, the study also calls for a re-examination of the indispensable role that medical infrastructure plays in the application of vaccine science.

Key Words: Smallpox; Cowpox; Arm-to-arm method; Infrastructure; Vaccine