The U.S. declared measles eradicated in 2000 but refusal to vaccinate children among certain pockets of the population means the disease is resurging. Public health officials in this country say 10 states have reported cases in 2019 alone. Internationally, the World Health Organization recently named “vaccine hesitancy” as one of the top global threats of 2019.

How do public health officials confront those opposed to vaccination? And why has the movement proved so resilient? Diane talks with Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health.