There were many factors influencing the development of vaccines in the later part of the 19th century. Edward Jenner was the first man to begin the idea of vaccinations when he developed a vaccine against smallpox in 1798. Jenner's work established a new practise. The idea of infecting patients with a milder form of a disease had not been done before. Jenner began this practise, and injected a patient of his, ... succeeded in doing this. Robert Koch used stains, microscopes, photography, and gels to observe and prove how some bacterial diseases worked and acted. This helped him to prove that ...

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