With the return of vaccine-preventable diseases and related conspiracy theories on the rise, PBS NOVA decided to investigate the state of immunization in America.
"Immunization plays a crucial role in our public health, yet there is a tremendous amount of apprehension and confusion around the topic," said Paula S. Apsell, senior executive producer for NOVA. So a new documentary — "Vaccines—Calling the Shots" — examines vaccine trends and the science behind them.
You can watch the whole thing here on Wednesday Sept. 10. For now, check out this clip that explains the concept of immunity in two minutes.