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
History of smallpox in Mexico 1799. Viceroy Miguel José de Azanza, ordered an article written on 14 November 1799 about the benefits resulting from the inoculation in the 1790s epidemic and distributed to the population. In 1803, Spanish doctor Francisco Javier Balmis started a vaccination program against smallpox in New Spain, better known as Balmis Expedition, which reduced the severity and mortality in the epidemics that followed. Before Balmis, Dr José María Arboleyda started a vaccination campaign in 1801 but this was not successful. There was another important outbreak in 1814 which started in Veracruz and extended to Mexico City, Tlaxcala and Hidalgo. This epidemic