Jenners method

An example of the Scientific Method in Vaccine History: Jenner’s method.


People who have had cowpox do not become ill with smallpox
If a person has been intentionally infected with cowpox, then that person will be protected from becoming ill after a purposeful exposure to smallpox.
Infect a person with cowpox. Then try to infect the person with smallpox (Note that Jenner did not use a control group in his experiment)
Infecting a person with cowpox protects from infection with smallpox. Jenner repeated his experiment several times and got the same results. Other scientists did likewise and got the same results. Jenner is famous for having applied the scientific method to establishing the means of preventing smallpox.


source: college of physicians of Philadelphia