When Edward Jenner created the first vaccine against smallpox, he had no idea what caused smallpox. The scientific appreciation of “germ theory” was just the start of the process of understanding microbiology. The History Guy recalls the forgotten history of the scientific study of “germs,” and how early germ theory actually delayed the scientific discovery of viruses.

This is original content based on research by The History Guy. Images in the Public Domain are carefully selected and provide illustration. As very few images of the actual event are available in the Public Domain, images of similar objects and events are used for illustration.