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
Smallpox vaccine intensive care units, anesthesiologists, and health care workers in other settings who would be crucial first-line responders in the event of a bioterrorist attack using smallpox. Many healthcare workers refused, worried about vaccine side effects, but many others volunteered. It is unclear how many actually received the vaccine. In 2002, the Israeli Army, in a similar attempt at mass vaccination, found many soldiers unwilling to volunteer. In May 2007, the Vaccines and Related Biological Products Advisory Committee of the FDA voted unanimously that a new live virus vaccine produced by Acambis, ACAM2000, is both safe and effective for use in