What is cowpox pus

What is cowpox pus?
Cowpox pus is the residues in cowpox infected skin area of cows.
At the end of 19th Century, it was used widely as a vaccine for prevention against the more deadly small pox disease in human after the English physician Edward Jenner researched for many years in it.


2012-10-27 18:26:15 補充：
By 1980, the World Health Organisation declared that the world is free from small pox. This is a direct result from the discovery of using cowpox 'pus' as a preventive vaccine against small pox in late 19th Century.