Anthrax vaccines known to result in far less scarring, and greatly reduced mortality, in comparison with the naturally acquired disease. The English physician Edward Jenner (1749–1823) had also discovered (1796) the process of vaccination by using cowpox to give cross-immunity to smallpox and by Pasteur's time this had generally replaced the use of actual smallpox material in inoculation. The difference between smallpox vaccination and anthrax or chicken cholera vaccination was that the weakened form of the latter two disease organisms had been "generated artificially", so a naturally weak form of the disease organism did not need to be found. This discovery revolutionized
1947 New York City smallpox outbreak died May 7, a week after receiving her vaccination. According to the Center for Disease Control, the rate for post-vaccination encephalitis following the smallpox vaccine is 3 to 12 per million, and the fatality rate is about 1 in a million. (Since this was the largest vaccination campaign ever, it is likely to have contributed substantially to the C.D.C.'s data and estimates.) Even President Harry S. Truman received a vaccination for a brief trip to give a speech in New York City to news reporters. There were two additional cases of smallpox transmitted in the New York City area at