The U.S. Food and Drug Administration is undergoing another leadership shift, as its top vaccine official has stepped down once again and a new acting director has been appointed to fill the role.
Dr. Vinay Prasad, who led the agency’s Center for Biologics Evaluation and Research (CBER), officially departed on April 30. The division is responsible for reviewing experimental vaccines and other biologic products submitted for federal approval.
Following his exit, Katherine Szarama, previously the center’s deputy director, has been elevated to serve as acting director, according to a spokesperson for the U.S. Department of Health and Human Services, which oversees the FDA.
Dr. Tracy Beth Hoeg, who currently leads another FDA center in an acting capacity, publicly thanked Prasad for his work, describing his tenure as “transformational” in a post on X.
Prasad had originally been brought into FDA leadership in 2025 by Commissioner Marty Makary, following the resignation of former CBER chief Peter Marks amid reported disagreements with Health and Human Services Secretary Robert F. Kennedy Jr..
A professor at the University of California, San Francisco, Prasad gained national attention during the COVID-19 pandemic for questioning aspects of federal health policy, including the broad push for vaccinations among younger populations.
His tenure at the FDA has not been without turbulence. He initially stepped away from the agency shortly after taking the role, following scrutiny over past social media activity. According to Makary, Prasad chose to step aside at the time to avoid becoming a distraction amid media coverage.
He later returned in August 2025 to lead CBER, with federal officials emphasizing that the agency’s work would continue despite outside criticism.
CBER plays a central role in evaluating vaccines, gene therapies and other biologic treatments, weighing potential risks and benefits before granting approvals. In recent months, some of its decisions have drawn criticism from lawmakers on both sides of the aisle.
Sen. Ron Johnson has publicly questioned the FDA’s handling of treatments for rare diseases, including its decision not to approve ataluren for Duchenne muscular dystrophy.
The agency has also faced pushback over its rejection of a skin cancer treatment developed by Replimune. Speaking to senators in April, Kennedy said the drug appeared ineffective based on internal FDA assessments and discussions with Makary, adding that the decision was made independently by the agency.
With new leadership now in place at CBER, attention is likely to remain on how the FDA navigates ongoing debates over drug approvals, vaccine oversight and regulatory standards.
