A 1905 Supreme Court case resulting from a smallpox outbreak empowered states to pass laws for the "health, peace, morals, education and good order of the people." So yes, you have to wear that mask.

Susan Sontag in conversation with Bill Moyers

Jon Palfreman, producer of Frontline's "The Vaccine War", shares what he discovered and how it applies to the current debate.

Use an interactive map from the Council on Foreign Relations to plot vaccine-preventable outbreaks around the world.