Vaccination disease people tried to prevent by inoculation and was the first disease for which a vaccine was produced. The smallpox vaccine was invented in 1796 by English physician Edward Jenner and although at least six people had used the same principles years earlier he was the first to publish evidence that it was effective and to provide advice on its production. Louis Pasteur furthered the concept through his work in microbiology. The immunization was called "vaccination" because it was derived from a virus affecting cows ( 'cow'). Smallpox was a contagious and deadly disease, causing the deaths of 20–60% of
1837 Great Plains smallpox epidemic were critical to limiting the spread of smallpox in Canada. After the epidemic the HBC implemented a territory wide vaccination program which further reduced smallpox deaths. Unfortunately, as people entered communities with the intention of vaccinating against smallpox, they brought with them additional diseases that worked to keep mortality rates high. The epidemic would alter power structures of impacted nations. As the Assinboine and Niitsitapi did not get the opportunity for vaccination and as a result both their populations and territory shrunk considerably. The disease was particularly deadly among these people because of the denser populations. After being hit by