What did edward Jenners jabs consist of?

Edward Jenner's jabs, developed in the late 18th century, consisted of material taken from cowpox lesions. He famously inoculated a young boy with this material to provide immunity against smallpox, demonstrating that exposure to a less severe disease could protect against a more severe one. This groundbreaking work laid the foundation for the field of immunology and the development of vaccines. Jenner's method effectively introduced the concept of vaccination, leading to the eventual eradication of smallpox.