The vaccine chief at the US Food and Drug Administration (FDA) will step down in April after a series of controversial decisions

A key US Food and Drug Administration official overseeing vaccines and biotech treatments will step down from the agency after multiple decisions that raised concerns within the industry.

Vinay Prasad, director of the Center for Biological Evaluation and Research, will leave the FDA at the end of April, an agency spokesperson confirmed on Friday. This is his second resignation from the position: he briefly left the position in July after a backlash over his organizational decisions, and returned just two weeks later in August.

In a post on X, FDA Commissioner Marty McCurry said the FDA will appoint a successor before Prasad returns next month to the University of California, San Francisco, where he taught before taking the FDA job last year. Makary said Prasad “accomplished a tremendous amount” during his time at the agency.

Prasad’s decision to step down comes after mounting criticism of the FDA within the biotechnology and pharmaceutical industry and among former health officials. Last year, the agency rejected or discouraged approval applications for at least eight drugs, according to RTW Investments, after it objected to data the companies used to support their applications. The US Food and Drug Administration also refused to review Moderna’s flu vaccine before changing course.

All of these companies accused the FDA of reversing previous guidance on what evidence could be used to support their applications, sparking criticism within the industry that an unreliable regulatory process could stifle drug development for hard-to-treat diseases.

A former FDA official who spoke to CNBC on the condition of anonymity to speak freely about the issue described the reversals as the worst kind of regulatory uncertainty because companies say they are told one thing and then face another.

In a statement issued earlier Friday, an FDA spokesperson said there was “no regulatory uncertainty,” adding that the agency “makes decisions based on evidence, but makes no guarantees about results.” The FDA “conducts rigorous, independent reviews and not rubber-stamp approvals,” the spokesperson said.

The latest controversy came after the Food and Drug Administration discouraged it UniQure of applying for accelerated approval for an experimental treatment for Huntington’s disease.

The agency, which has undergone staff cuts and an overhaul under Health and Human Services Secretary Robert F. Kennedy Jr., has faced a broader backlash to its drug and vaccine approval process. Critics have expressed concern that the agency could stifle the development of new treatments and risk patient safety.

The Wall Street Journal had earlier reported Prasad’s departure.