For many years, he heard stories that dairymaids don’t get smallpox if they’ve had cowpox previously. Dairymaids spend a lot of time with cows to make milk or cheeses in a dairy.

This pic is cowpox. (2/6)
A young dairymaid had fresh cowpox. Jenner transferred some material from her skin lesions to an 8-year old boy’s skin. The boy had some mild fever but was otherwise quite well.

2 months later, Jenner repeated with smallpox but the boy had no fever.

This pic is smallpox. (3/6)
This proves the theory that “giving people very small amounts of a virus or bacteria can trigger their immune system to help fight future infections of the same virus or bacteria”.

This pic shows how vaccines work. (4/6)
The Latin word for cow is vacca, and cowpox is vaccinia.

Therefore, Jenner decided to call this new concept “vaccination”. (5/6)
Although… some historians think that Jenner used horsepox, not cowpox. So instead of vaccine, perhaps we should call it “equusine”!

This shows that science continues to progress, because our instruments & tools become more precise & sophisticated. https://abs.twimg.com/emoji/v2/... draggable="false" alt="🧪" title="Test tube" aria-label="Emoji: Test tube">https://abs.twimg.com/emoji/v2/... draggable="false" alt="🔬" title="Mikroskop" aria-label="Emoji: Mikroskop">https://abs.twimg.com/emoji/v2/... draggable="false" alt="🧬" title="DNA" aria-label="Emoji: DNA">https://abs.twimg.com/emoji/v2/... draggable="false" alt="💉" title="Spritze" aria-label="Emoji: Spritze"> (6/6)
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