Before reading Eula Biss's new book "On Immunity," I thought the anti-vaccination movement was a recent phenomenon. But as she makes clear, the roots go much deeper: not only historically, but psychologically, sociologically, maybe even theologically. We talked about vaccines and their safety, the history of inoculation and its discontents, public vs. personal health, choosing what to fear, purity and pollution, illness as metaphor, and vampires.