"What does a cow called blossom have to do with vaccines? Let's head back to 1796.
A contagious disease was spreading throughout the United Kingdom. Symptoms included high fevers and sores developing on the skin. This disease was called smallpox.
Then along came Edward Jenner, a physician in the English countryside. He saw many patients who had smallpox, but noticed that some people didn't contract the disease. These people were milkmaids. Milkmaids were more likely to get another disease called cowpox. Cowpox somehow stopped them from getting smallpox, and Jenner started to take note.
Then along came Blossom. Jenner took the scab of Sarah Nelmes, who'd contracted
cowpox from the cow called Blossom. He transmitted the matter of the scab to a young boy, James, infecting him with cowpox. James initially got sick, but after a few days, made a full recovery. Jenner then infected James with smallpox in the same manner as before. He held his breath and waited to see the results of his experiment. James didn’t develop smallpox- he'd built immunity to the disease. Jenner had discovered vaccination.
Five years after this discovery, the College started the UK's first public vaccination center, vaccinating members of the public against smallpox.
So that's what a cow called Blossom has to do with vaccines."