For most of human history, infectious diseases have wreaked havoc on humans. But beginning in the late 18th century, more and more of us beat back illness by getting immunized with vaccines. Today, vaccines are -- or should be – a part of every thinking person’s health regimen.

But exactly what are vaccines and how do they work? How are they tested?

Joining Jim in this episode of Point of Inquiry is immunologist David Miles. David teaches at London School of Hygiene and Tropical Medicine, and is the author of How Vaccines Work: A layman's guide to the history and science of vaccines and vaccination.

Learn about both the history and present state of immunology from this fascinating discussion.