Mozart and smallpox the imperial family were successful, and led to greater public acceptance for the procedure. Smallpox struck the Mozart family again in the next generation: Nannerl's eldest son Leopold and two of her stepchildren caught the disease during an outbreak in the Salzburg area in 1787. All three children survived. In 1796, the discovery of vaccination—the use of the related cowpox virus to immunize against smallpox—by Edward Jenner revolutionized the ability of medicine to deal with smallpox. Vaccination reached Vienna around 1800, when yet another local epidemic created impetus for its adoption. One of the doctors trained in the Vienna campaign,
1974 smallpox epidemic in India the last cases of smallpox, called "Target Zero", with the identification of the last smallpox patient in India occurring on May 24, 1975. By 1980, smallpox was certified as being eradicated from the world. Smallpox was eradicated due to the WHO's smallpox eradication program. This program was formally established in 1958, but because of logistics disagreements between the WHO and the Indian government, did not progress rapidly. Headway only began to take place in India after the reorganization of the WHO in the mid 1960s. Donald Henderson, who was a U.S. Public Health Services Officer stationed in New Delhi, said