Who discovered the smallpox vaccine?

• A. Edward Jenner
• B. Louis Pasteur
• C. Robert Koch
• D. Joseph Lister

Answer: (A)

The main idea here is how protection against a deadly disease was first created by using a milder, related virus to train the immune system. Edward Jenner recognized that milkmaids who had contracted cowpox seemed protected from smallpox. He hypothesized that cowpox exposure could confer immunity to smallpox. To test this, he inoculated a young boy with material from a cowpox lesion and later exposed him to smallpox; the boy did not develop smallpox. This demonstrated that a safer infection could provide lasting immunity against a more dangerous one, forming the basis of vaccination. The term vaccine comes from vacca, meaning cow, reflecting the cowpox origin of the first successful protection. While other scientists like Pasteur, Koch, and Lister advanced microbiology and medicine later, Jenner is the one who discovered the smallpox vaccine.