The first successful vaccination was developed in 1796 by Edward Jenner, who pioneered the use of cowpox material to confer immunity against smallpox. Jenner's ground-breaking work demonstrated that exposure to a less virulent virus could protect against a more dangerous one. This marked the beginning of immunology and vaccination practices, leading to widespread efforts to combat infectious diseases. The success of Jenner's method paved the way for future developments in vaccination and public health, eventually contributing to the global eradication of smallpox in the late 20th century.