Jay Bhattacharya, director of the National Institutes of Health, has been appointed acting director of the Centers for Disease Control and Prevention in an unusual dual role. This move comes during a leadership shakeup at the Department of Health and Human Services under Health Secretary Robert F. Kennedy Jr.

The appointment follows the ouster of Susan Monarez, who briefly served as CDC director before being removed for refusing to rubber-stamp Kennedy's anti-vaccine changes. Jim O'Neill then held the position briefly before being reassigned to potentially lead the National Science Foundation.

Researchers and public health experts have sharply criticized the appointment, citing Bhattacharya's lack of hands-on leadership at NIH. Under his watch, the agency terminated or froze hundreds of millions in research grants, including $561 million for studies on America's leading causes of death, and defunded at least 304 clinical trials. Sixteen of NIH's 27 institutes currently lack directors. Critics describe Bhattacharya as more focused on public interviews than agency management, earning him the nickname "Podcast Jay." Public health advocates warn that his leadership at both agencies during a time of rising preventable diseases like measles represents a dangerous escalation of Kennedy's anti-vaccine agenda.