... The tiny specimen, found carefully wrapped inside a letter dated 1876 that a Richmond man mailed to his father in Charlottesville, provides a glimpse of what would evolve into modern day immunization.
"Dear Pa … the piece I inclose is perfectly fresh and was taken from an infant's arm yesterday. …" the letter read. "Dr. Harris says the inclosed scab will vaccinate 12 persons, but if you want more, you must send for it. I will pin this to the letter so that you cannot lose it as you did before" ...
Two days later, CDC staffers donning protective gear seized the skin and took it back to their Atlanta headquarters to study its scabby secrets and ensure it was no longer infectious.
"We did testing to look for evidence of variola," the most severe form of the smallpox virus, "and it was negative," said Dr. Inger Damon, chief of the CDC's pox and rabies branch ...
http://abcnews.go.com/Health/Wellness/smallpox-scab-removed-virgina-museum-bizarre-bits-exhibit/story?id=13646873