Smallpox disappearing is entirely due to global efforts of administering the smallpox vaccine. When my children were small and getting immunizations, I asked their pediatrician if they would get the smallpox vaccine. He laughed at that and said "no" - he was enough younger than me that perhaps he didn't get the smallpox vaccine at school like I did, and my siblings, and every child in the state as far as I know (this was still being administered in the early 1960s.) It wasn't a choice, everyone got it. Science and medical common sense ruled.