By Josh Nathan-Kazis

Biotech and pharmaceutical stocks were sliding Tuesday afternoon as the Food and Drug Administration named Dr. Vinay Prasad, a critic of FDA policy and the U.S. Covid-19 response, as its top vaccine regulator.

Prasad succeeds Dr. Peter Marks, who left the role of leader of the FDA's Center for Biologics Evaluation and Research in March, writing in his resignation letter that Robert F. Kennedy Jr., the secretary of Health and Human Services, "wishes subservient confirmation of his misinformation and lies." Marks was perhaps the best-known career official within the agency.

Shares of biotech companies began to fall after various outlets reported Prasad's selection around 12:30 p.m. Eastern. The SPDR S&P Biotech ETF, trading at $80.11 at 12:30 p.m., fell to $77.95 over the next hour, a 2.7% drop.

Shares of Moderna shares were down 10% for the day. Prasad has raised questions about the safety of Covid-19 vaccines. In late April, he published a Substack post arguing for a change to the FDA's regulatory approach to Covid-19 booster shots that would require companies to run randomized clinical trials of each updated version of the shot.

Novavax, another Covid-19 vaccine maker, was down 6.7%.

Big pharma stocks with significant vaccine businesses were falling as well. American depositary receipt of GSK, which was roughly flat on the day as of 12:30 p.m., was down 1.7% by 1:30 p.m. Merck, another large vaccine maker, was down 4.6%, while Pfizer fell 3.3.%

In a post on the social media site X, FDA Commissioner Dr. Marty Makary wrote that Prasad "brings the kind of scientific rigor, independence, and transparency we need at CBER -- a significant step forward."

Write to Josh Nathan-Kazis at josh.nathan-kazis@barrons.com

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May 06, 2025 14:04 ET (18:04 GMT)

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