Joe Hanson of It’s Okay To Be Smart attempts to answer the question, “Why vaccines work?”
He begins by going through a medical history of scurvy and polio. Hanson also explains how the body fights infections and build immunity. As adults, we’re immune to many viruses compared to a child, who have young immune systems. Vaccines work by introducing the body to a weakened version of a virus. It allows the immune system to build its army of memory cells against infections like polio or measles. Hanson also explains that the lack of vaccination has led to viruses making a comeback.
Source: It’s Okay To Be Smart