The Fired C.D.C. Director Testifies

For weeks, fights have been escalating between top scientists at the Centers for Disease Control and Prevention and the health secretary, Robert F. Kennedy Jr., culminating in his accusation that the agency’s top official, Dr. Susan Monarez, was untrustworthy.

Dr. Monarez went before a Senate committee on Wednesday to give her side of the story.

Sheryl Gay Stolberg, who covers health policy for The New York Times, discusses the testimony and the rift that the hearing exposed within the Republican Party over how far to go to support Mr. Kennedy and his vaccine agenda.