James Donald writes:
The original vaccine was based on cowpox, the nearest relative of small pox. However it was insufficiently effective and reliable, and so was furtively replaced by a weakened strain of smallpox, which was grown on cows. The sellers of the vaccine continued to represent it as cowpox, but it was in fact a mild variant of the real thing, smallpox.
One reason for ending routine smallpox vaccinations was fear that the vaccine might re-evolve virulence.
You are full of shit. The smallpox vaccine is not made from cowpox or from smallpox (variola) virus. It is made from the vaccinia virus. Did you ever wonder where the word "vaccine" comes from? The reason routine smallpox vaccinations ended was because some people have a bad reaction to the vaccinia virus, even though a strain is used that is generally benign. Since the vaccination was thought to confer no benefit and does carry some risk, it was discontinued. Do a google search on "smallpox vaccine" next time before you spout off with ignorant garbage like this.