(Reuters) -The U.S. Food and Drug Administration has named Vinay Prasad, an oncologist who has previously criticized FDA leadership and COVID-19 mandates, as the director of its Center for Biologics Evaluation and Research, the agency said on Tuesday.

In that role, Prasad, a frequent critic of the pharmaceutical industry, will oversee the regulation of costly and complicated biologic drugs, including vaccines, gene therapies, and blood supply. He succeeds Peter Marks, who oversaw the approval of COVID-19 vaccines and was pushed out of the agency in March.

Drug company stocks fell on the news, led by an 11% drop in vaccine maker Moderna and a 20% fall in shares of smaller gene therapy developers.

In a recent blog post on the Substack platform, Prasad said the CDC "should ABSOLUTELY remove COVID-19 from the Childhood Immunization schedule. If it stays, it shows the United States is a corrupt country," citing the lack of randomized trial evidence for use of the vaccines in children.

In another post, Prasad criticized media coverage of Marks' departure and called him "one of the most dangerous, pro-pharma regulators of the 21st century."

In a note to clients, RBC Capital Markets analyst Brian Abrahams called Prasad an "anti-establishment physician" who has been vocal on a broad range of matters, "including COVID-19, oncology studies, and randomized clinical trial designs in general."

Abrahams noted that Prasad has been particularly critical of Marks' support of Sarepta Therapeutics' gene therapy treatment for Duchenne muscular dystrophy.

Pfizer shares fell 3%. Smaller gene therapy developers such as Sarepta and Taysha Gene Therapies plunged about 20%.

A basket of biotech shares, the SPDR S&P biotech ETF, fell 6%. It has fallen about 9% since Robert F. Kennedy Jr., a vaccine critic, was confirmed as U.S. health secretary in February.

Prasad is not without supporters, however.

The FDA's commissioner, Marty Makary, announced Prasad's appointment in an email to staff. 

"He brings a great set of skills, energy, and competence to the FDA, and I know that he is eager to begin immersing himself in the important work of CBER and the agency as a whole," Makary wrote.

Walid Gellad, a physician from the University of Pittsburgh, said Prasad is "a brilliant guy with remarkable experience understanding evidence and data on drugs. He has a difficult task ahead but an opportunity to bring those talents to positively impact FDA and the American public."

Scott Steele had been serving as acting head of CBER.

Prasad comes to the FDA from the University of California, San Francisco. He holds a medical degree from the University of Chicago, and has had stints at the National Cancer Institute and the National Institutes of Health.