Part 1. (The part everyone knows about)
Dr Jenner noticed that milk-maids never seemed to suffer from small pox, although suffered from the non-lethal cow-pox, due to being in constant contact with cows.
Dr Jenner concluded that the cow-pox made the immune systems of the milk maids resistant to the deadly small pox, and therefore intentionally infected his own 8 year old son, and his gardener's son also, with cow pox in order to inoculate them against small pox.
It worked! Neither Jenner's son or his gardener's son contracted small pox and the era of vaccinations was born!
Part 2. (The part that nobody ever hears about).
Although neither of the boys contracted small pox, they did suffer from a much nastier bout of cow pox than was typical. After they recovered from the cow pox which did not kill them, their health was poor suffering from regular bouts of illness, with both suffering from some form of mental retardation that was not manifest prior to the inoculations. Both boys died young. Jenner's son reached only 21 years of age.......
.........but at least he never died from small pox!
Now all you motherfucker anti-vaxxers! Get your little disease spreading brats down to your nearest vax clinic and have their veins pumped full of damaged viruses and a cocktail of other toxic shit. If you don't, you will be deemed by social services to be an abusive parent and they will take your brats off you, put them in a care home, where they will be routinely raped by politicians, aristocrats, and the odd celebrity who will take all the rap for it, 50 years down the line, after they are dead.