Edward Jenner is credited with developing the first vaccine. In the late 18th century, Jenner conducted experiments using cowpox virus to protect against smallpox, a deadly disease that plagued populations for centuries. His pioneering work in 1796 involved inoculating a young boy with material taken from a cowpox sore, demonstrating that it provided immunity to smallpox. Jenner’s findings laid the foundation for modern immunology and vaccination practices, significantly reducing the impact of infectious diseases. His contributions are celebrated as a turning point in public health and have saved countless lives throughout history.