Rumors are spreading all over the place.’ Experts fear the cancellation signals a sidelining of science at federal health agencies under Robert F. Kennedy Jr.’s leadership.

This week, the Food and Drug Administration — now with vaccine skeptic Robert F. Kennedy Jr. at the helm — unexpectedly and without reason canceled a March meeting of scientists who advise the FDA on vaccine policy. A similar meeting at the Centers for Disease Control was postponed last week.

Two long-planned vaccine meetings — one at the US Centers for Disease Control and another at the US Food and Drug Administration — have now been disrupted under the watch of US Health and Human Services Secretary Robert F.