An examination of the consequences of vaccine hesitancy and denial. It's a war anti-vax activists have been fighting for a decade. And COVID-19 is what they practiced for: A national conversation about vaccine safety.

A Perilous Quest to Save the World’s Children tells the inspiring story of Dr. Maurice R. Hilleman, a man with a singular, unwavering focus — to eliminate the diseases of children. From his poverty-stricken youth on the plains of Montana, he came to prevent pandemic flu, develop the measles-mumps-rubella (MMR) vaccine, and invent the first-ever vaccine against human cancer.

Tracing the dramatic and controversial rise of Robert F. Kennedy Jr., FRONTLINE examines how the scion of a storied dynasty endured tragedy and scandal, broke with the Democratic Party and his family, stoked conspiracy theories, and is reshaping government and public health.

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.