Who discovered the smallpox vaccine and in what year ?

In 1796, the British doctor Edward Jenner demonstrated that an infection with the relatively mild cowpox virus conferred immunity against the deadly smallpox virus. Cowpox served as a natural vaccine until the modern smallpox vaccine emerged in the 19th century.

the question is asking about the things that may have affected and what they effects had on the spanish conquest and settlement of america

explanation:

- "bill clinton ( the 42nd u.s. president, served in office from by low unemployment, declining crime rates and a budget surplus. during clinton's second term, the u.s. economy was healthy, unemployment was low and the nation experienced a major technology boom and the rise of the internet."