As the epidemic raged on, a Boston physician announced that he could expose people to the virus in a way that would give them a much milder, less dangerous infection – and then protect them from smallpox for the rest of their lives.
As the epidemic raged on, a Boston physician announced that he could expose people to the virus in a way that would give them a much milder, less dangerous infection – and then protect them from smallpox for the rest of their lives.