U.S. Health Secretary Robert F. Kennedy Jr.'s surprise ouster of a national vaccine advisory board, claiming it was "plagued with persistent conflicts of interest," puts new scrutiny on the group that recommends which shots should be administered to the American public.

The health secretary cited financial conflicts, but a White House official and someone familiar with his thinking said he was also concerned about ties to Democrats.

The Advisory Committee on Immunization Practices helps the agency make recommendations on who should get certain vaccines.