Kennedy Jr. told a room packed with federal health workers on Tuesday that he plans to "investigate" whether the timing of childhood vaccinations and anti-depression medications are among several "possible factors" in the nation's problem with chronic diseases.

Del Bigtree, now a leader of Robert F. Kennedy Jr.’s grassroots movement, said he should seek proof of an autism link.

To earn the vote he needed to become the nation’s top health official, Robert F. Kennedy Jr. made a promise: He would not change the nation’s current vaccination schedule. But on Tuesday, he vowed