Short answers, pulled from the story.
Edward Jenner, a British physician born in Berkeley, England, demonstrated in 1796 that infection with cowpox conferred immunity against smallpox. He published his findings in 1798 in An Inquiry into the Causes and Effects of the Variolae Vaccinae. Jenner was not the first to try cowpox inoculation, but he was the first to publish evidence and distribute vaccine freely.
Smallpox was declared eradicated in December 1979, confirmed by a Global Commission chaired by Frank Fenner and endorsed by the WHO General Assembly in May 1980. A WHO eradication campaign running from 1967 combined international outbreak surveillance with targeted vaccination. The last endemic case occurred in Somalia in October 1977.
First-generation vaccines are grown on the skin of live animals such as calves and sheep; second-generation vaccines are grown in chorioallantoic membrane or cell culture for greater purity; third-generation vaccines use attenuated vaccinia strains with fewer side effects. All three generations remain available in stockpiles. First and second-generation vaccines contain live unattenuated vaccinia virus and can cause death in 1-10 people per million vaccinations.
MVA-BN, sold as Jynneos in the United States, Imvanex in the European Union, and Imvamune in Canada, is a third-generation smallpox vaccine manufactured by Bavarian Nordic. It is based on Modified vaccinia Ankara, a replication-incompetent vaccinia variant developed in West Germany through 572 serial passages. MVA-BN has been approved for both smallpox and mpox.
The word vaccine derives from the Latin vacca, meaning cow, reflecting the origins of smallpox vaccination. Edward Jenner named the virus vaccinia after the Latin word for cow. The term vaccination, first used in print by Jenner's friend Richard Dunning in 1800, initially referred only to smallpox; in 1881 Louis Pasteur proposed at the 7th International Congress of Medicine that the term be widened to cover all protective inoculations.
Variolation was the practice of deliberately inoculating a healthy person with material from a mild smallpox case to induce immunity. The first clear written reference appears in Wan Quan's Douzhen xinfa, published in 1549. It carried a mortality rate of 0.5-2.0%, compared with 20-30% for natural smallpox infection. Jenner's vaccine used cowpox rather than smallpox, reducing the risk further and eventually replacing variolation entirely.