After inoculation, vaccination using the cowpox virus became the primary defense against smallpox. After infection by the cowpox virus, the body (usually) gains the ability to recognize the similar smallpox virus from its antigens and is able to fight the smallpox disease much more efficiently.

How did they cure smallpox?

There is no cure for smallpox, but vaccination can be used very effectively to prevent infection from developing if given during a period of up to four days after a person has been exposed to the virus. This is the strategy that was used to eradicate the disease during the 20th century.

What was the original treatment for smallpox?

One of the first methods for controlling smallpox was variolation, a process named after the virus that causes smallpox (variola virus).