World History: the Origins of the Smallpox Vaccine
Why we can thank cows and milkmaids for being smallpox-free these days. [Brooklyn Brainery]
(Source: bkbrains)
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hellomsg reblogged this from bkbrains and added:
Why we can thank cows and milkmaids for being smallpox-free these days. [Brooklyn Brainery]
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bkbrains posted this
