Public health scientists and clinicians tout vaccines as one of the greatest achievements of modern medicine. But for many ordinary Americans vaccines have become controversial. Young parents are concerned at the sheer number of shots — some 26 inoculations for 14 different diseases by age 6 — and follow alternative vaccination schedules. Other parents go further. In communities like Ashland, Oregon, up to one-third of parents are choosing not to vaccinate their kids at all. This is the vaccine war: On one side sits scientific medicine and the public health establishment; on the other a populist coalition of parents, celebrities, politicians and activists.