The unusual dual role has renewed criticism of Bhattacharya's lack of leadership.

HHS Deputy Security Jim O'Neill is currently acting CDC director, having taken over in August after HHS Sec. Robert F. Kennedy Jr. fired the former director.

RFK Jr ally Jay Bhattacharya was named acting director of the CDC and will be fourth leader in a year to head agency

The unusual dual role has renewed criticism of Bhattacharya's lack of leadership.