Original broadcast date: August 28, 2005

In a June Rolling Stone article, and in subsequent appearances on Imus in the Morning, ABC News, and The Daily Show With Jon Stewart, Bobby Kennedy Jr accuses US government vaccine scientists and their academic advisers of covering up what for him is an uncontestable fact: the causal link between a mercury-containing preservative called thimerosal in vaccines and a massive increase in childhood autism in America.

This is but a sliver of statements made by people concerned about the side effects of vaccines. But are these statements supported by evidence? What evidence do we have that provides a true picture of the effects vaccines have on society?

• Arthur Allen, freelance writer and contributor (science and health) to slate.com and currently writing a history of vaccination.