Both Democratic and Republican senators grilled Health and Human Services Secretary Robert F. Kennedy Jr. on Thursday in a contentious hearing on his policies and anti-vaccine misinformation. RFK fired the head of the Centers for Disease Control and Prevention last week, causing turmoil at the agency, and this week 1,000 current and former HHS employees sent a letter to Congress demanding his resignation. “Robert F. Kennedy Jr. has a 20-year history of being an anti-vaccine propagandist, science denialist and conspiracy theorist,” says Dr. Paul Offit, director of the Vaccine Education Center and a physician at the Children’s Hospital of Philadelphia. Offit was removed from the Food and Drug Administration’s vaccine advisory committee last week without explanation and says Kennedy’s undermining of public health is “causing children to die unnecessarily.”