“What they’re saying when they make these appointments is that we don’t trust the people who are there,” said Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia and an adviser to the Food and Drug Administration. Some doctors and scientists are bracing themselves for the gutting of public health agencies, a loss of scientific expertise and the injection of politics into realms once reserved for academics. The result, they fear, could be worse health outcomes, more preventable deaths and a reduced ability to respond to looming health threats, like the next pandemic. “I’m very, very worried about the way that this all plays out,” Dr. Offit said.