Vaccine stocks fall after key FDA official resigns in protest of RFK Jr.

Shares of Moderna, Novavax and other biotech companies fell after FDA official Peter Marks's resignation in protest of Robert F. Kennedy Jr.

Vaccine stocks fall after key FDA official resigns in protest of RFK Jr.

Rafael Henrique | Lightrocket | Getty Images

Shares of major vaccine makers dropped on Monday after a key U.S. health official resigned in protest of Health and Human Services Secretary Robert F. Kennedy Jr.'s views on immunization.

The departure of Peter Marks, the Food and Drug Administration's top vaccine regulator, has raised fresh fears about whether the Trump administration will quickly approve and promote critical shots. In his position, Marks oversaw the introduction of Covid-19 vaccines and rules for the use of emerging treatments like cell and gene therapies.

Shares of Moderna and Novavax dropped more than 11% and 6%, respectively, in early trading. Meanwhile, the SPDR S&P Biotech ETF slid nearly 5%. Shares of Pfizer, which has broader businesses to insulate it from damage to its vaccine portfolio, lost about 2%.

Some Wall Street analysts said Marks' departure could undermine the FDA's mission of ensuring safe and effective treatments reach patients in the U.S. That could put even more pressure on a struggling biotech sector.

"Taking a step back, we view this departure as a significant negative for the BioPharma and Biotech sectors, as FDA's independence rooted in sound scientific rigor is critical for their efficient functioning," analysts at BMO Capital Markets wrote in a note Monday.

Peter Marks, director of the center for biologics evaluation and research at the U.S. Food and Drug Administration (FDA), speaks during a Senate Health, Education, Labor, and Pensions Committee hearing in Washington, D.C., U.S., on Tuesday, May 11, 2021. 

Greg Nash | Bloomberg | Getty Images

In his resignation letter obtained by CNBC on Friday, Marks criticized Kennedy's "misinformation and lies" about immunization. He said a growing measles outbreak that started in Texas came as a consequence of "undermining confidence in well-established vaccines."

"As you are aware, I was willing to work to address the Secretary's concerns regarding vaccine safety and transparency by hearing from the public and implementing a variety of different public meetings and engagements with the National Academy of Sciences, Engineering, and Medicine," Marks wrote. "However, it has become clear that truth and transparency are not desired by the Secretary, but rather he wishes subservient confirmation of his misinformation and lies."

The Department of Health and Human Services did not immediately respond to a request for comment.

Kennedy, a prominent vaccine skeptic, has already taken steps that public health experts say could deter routine immunizations in the U.S. He has downplayed the importance of the measles, mumps and rubella vaccine and promoted unproven treatments to counter the measles outbreak. The Centers for Disease Control and Prevention is also carrying out a study into long debunked links between vaccines and autism, led by a researcher with a history of spreading misinformation about shots.

Analysts at Leerink Partners wrote in a Monday note that the effect of Marks' resignation on biotech and pharmaceutical stocks will depend in part on who replaces him at the FDA and whether Republicans in the White House and Congress start to lose patience with his approach. Other analysts also stressed that Marks is only one official at the agency and noted that new FDA Commissioner Marty Makary has a track record of supporting proven treatments.

"Though many believe the Marks resignation is a very bad omen for the Healthcare industry and innovation at large, it may be a bit premature to cast too dark of a shadow on the entirety of Pharma and Biotech," wrote Mizuho Securities analyst Jared Holz.

— CNBC's Angelica Peebles and Annika Kim Constantino contributed to this report