@Lomu history of the small pox vaccine. TLDR It never worked.
1717 was the first time small pox vaccine-style (variolation) was used. Lady Mary Montague brought back to UK (from Ottoman Empire) the technique of scratching a small amount of human smallpox lesion in to another person. Theory being, in a controlled time and place of patients choosing they stood better chance of beating it.
The problem was it spread the disease wider and the case wasn't always mild. Contemporaries estimated 2-3 people per 100 died from variolation/inoculation. By 1728 practice no longer popular in Europe.
Variolation rose and fell in UK/Europe/US over a couple decade'ish long waves as prominent doctors would promote it but then poor outcomes or society would quell it. One 1764 account said smallpox deaths were 90 per 1000 births and 64 per 1000 burials. After 38 years of inoculation smallpox deaths were 127 per 1000 births and 81 per 1000 burials. Inoculation increased small pox epidemics and death.
1774 diary farmer Benjamin Jesty scratched cox pocks into his wife and sons ad when exposed to small pox didn't get sick. Later, Doctor Edward Jenner repeated the process with an 8 year old boy James Phipps and claimed the process in 1798. Jenner experiments didnt include whether Phipps had a subclinical reaction or if he had prior immunity. There was no scientific method and the sample size was 1. Jenner claimed lifelong immunity, then changed to varying estimates of 10 years to 1 year.
Later different doctors promoted different times for re-vaccination ranging for 3 years to 1 year. None of them had produced a robust test of vaccinated versus unvaccinated.
There was confusion over where Jenner's pox came from. A 1829 Lancet study traced it to a lesion on a horse (not a cow). An 1834 article said there was so much confusion about the origin of and practice of producing the pox-agent (including cow, horse, donkey, sheep, rabbit, human) it was simply called the "vaccine virus".
1952 article in BMJ confirmed UK Ministry of Health had no idea the origin of the pox-agent they had used for vaccines.
Jener had lots of contemporaries who repeated his experiments and negated the theory. Dr Drake 1799, Dr Woodville also 1799 (one child died). An Medical Observer article in 1810 detailed 535 small pox cases after inoculation. 1817 London Medical Repository Monthly Journal also detailed the same. 1818 surgeon Thomas Brown showed the same. Lots of doctors showed publicly Jener's theory was not valid. but the practice continued to be promoted and paid well.
There's plenty more... especially how small pox vaccination drives (sometimes compulsory) through 1800 and 1900's would produce smallpox outbreaks, pandemics and death. The smallpox vaccine or "vaccine virus" cocktail did not cure the world of smallpox
