On May 14, 1796, English physician Edward Jenner administered the first smallpox vaccine, marking a significant milestone in the history of medicine and the fight against infectious diseases.

Smallpox was a devastating viral disease that had plagued humanity for centuries, causing millions of deaths and leaving survivors with disfiguring scars. Jenner had observed that milkmaids who had contracted cowpox, a milder disease, seemed to be immune to smallpox. This observation led him to hypothesize that inoculation with cowpox could protect against the more deadly smallpox virus.

To test his theory, Jenner took matter from a cowpox lesion on the hand of a milkmaid named Sarah Nelmes and inoculated it into the arm of an 8-year-old boy named James Phipps. Six weeks later, Jenner exposed Phipps to smallpox, but the boy did not contract the disease, proving that the cowpox inoculation had provided protection.

Jenner called this new procedure "vaccination," derived from the Latin word "vacca," meaning cow, in reference to the cowpox virus used in the inoculation. His groundbreaking work laid the foundation for the development of vaccines against many other diseases, including polio, measles, and influenza.

The impact of Jenner's discovery cannot be overstated. Vaccination has saved countless lives and has been instrumental in the eradication of smallpox, which was officially declared eradicated by the World Health Organization in 1980. Jenner's legacy continues to inspire scientists and medical professionals in their ongoing efforts to prevent and control infectious diseases through vaccination.