Who first introduced the idea of immunizations?

• A. Edward Jenner
• B. Louis Pasteur
• C. Jonas Salk
• D. Alexander Fleming

Answer: (A)

Immunization began with the idea that exposing the body to a harmless form of a pathogen can train the immune system to fight the real disease. Edward Jenner put that idea into practice by using material from cowpox to protect against smallpox. He observed that milkmaids who had cowpox didn’t get smallpox and tested the concept by inoculating a healthy boy with cowpox and later exposing him to smallpox; the boy remained healthy. This demonstrated that a deliberate, milder infection could confer protection, which is the essence of vaccination. Jenner’s work established the first successful vaccine and the practice of immunization, while others later expanded on vaccines for different diseases.