Edward Jenner noticed that milkmaids who had had cowpox did not catch smallpox…
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Edward Jenner noticed that milkmaids who had had cowpox did not catch smallpox. Explain what Jenner did next, and why it worked.
Need a reminder? The key ideaShow
The immune system, led by white blood cells, kills microbes and remembers them. A vaccine is a harmless form of a microbe that trains it. Edward Jenner used cowpox against smallpox. Vaccinating most of a community protects those who are not vaccinated. HIV attacks the white blood cells themselves.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. What he did. In 1796 Jenner scratched material from a cowpox sore into a boy's skin. The boy had a mild illness only.
Step 2. Why it worked. The immune system met the mild cowpox virus and remembered it. Cowpox is close to smallpox, so the defenders were ready when smallpox came.
Answer: Jenner gave a mild, harmless microbe to train the immune system. This was the first vaccine.
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