Robert F. Kennedy Jr. arrives in the lobby of Trump Tower in New York for a meeting with President-elect Donald Trump.

WASHINGTON — Outspoken vaccine critic Robert Kennedy Jr. said Tuesday that he had accepted a position in Donald Trump’s administration as chair of a panel on vaccine safety and scientific integrity, in what would be the clearest sign yet of the president-elect’s suspicions about vaccines.

Kennedy’s remarks followed his meeting with the president-elect at Trump Tower and immediately sparked outrage from scientists, pediatricians, and public health experts, who fear the incoming administration could give legitimacy to skeptics of childhood immunizations despite a huge body of scientific research demonstrating that vaccines are safe. Many of those skeptics believe vaccines are a cause of autism.