Edward Jenner's careful investigations into the usefulness of cowpox vaccination for the prevention of smallpox during the late 1790s, and his enthusiastic and continued advocation of vaccination despite the scepticism of critics, laid the foundations for the growth of understanding about the nature of infectious disease and the development of immunity during the 19th century. He began the long process which resulted in the successful eradication of the smallpox virus in 1980. His life story remains an inspiration to physicians facing an uncertain future as viruses and bacteria not yet eradicated adapt to the antibiotic age.