The Origins of the Word Vaccinate:
In 1796, Edward Jenner took some matter from a cowpox sore on the hand of dairymaid Sarah Nelmes, and inserted it into the arm of an eight-year-old boy…The boy was “perceptibly indisposed” on the ninth day, but recovered the following day. Six weeks later, Jenner inoculated him with matter taken from a smallpox pustule, “but no disease followed”…Jenner published 23 case studies to demonstrate the safety and efficacy of “vaccination,” as his procedure came to be called: vacca is the Latin term for cow, and vaccinia is another term for cowpox.
Freedman, D. A. (2010). On Types of Scientific Inquiry: The Role of Qualitative Reasoning. Rethinking Social Inquiry. H. E. Brady and D. Collier, Rowman and Littlefield: 221-236.