[realpatriot71]

More than 2000 years ago the Chinese prevented smallpox

Nope - you got smallpox, but the dz was usually not as terrible. Hey if you're going to get it anyway. . .

[Black Agnes]

True. The idea here was to expose the bodies immune system to the smallpox virus, but not in such great numbers that the immune system was overwhelmed and succumbed.

Interesting side note. In some African countries, in the countryside a significant percentage (30% IIRC) of the population shows antibodies to ebola. This means they are in contact with the vector in such a way that they are exposed enough to tickle their immune response but not enough to actually come down with ebola itself.

[Paleo Conservative]

More than 2000 years ago the Chinese prevented smallpox

Nope - you got smallpox, but the dz was usually not as terrible. Hey if you're going to get it anyway. . .

That technique is called variolination. It has about a 1% death rate and considerably milder symptoms compared to inhaling smallpox (the normal method of contracting the disease).