Two top FDA vaccine regulators are leaving

Dan Sfera
3 min readSep 2, 2021


Stepping Down

Marion Gruber and Phil Krause, two of the Food and Drug Administration’s top vaccine reviewers, are leaving the agency just as a decision on COVID-19 boosters is imminent. Both intend to step down from the FDA within the next two months.

Gruber, who has been with the FDA for three decades and is the head of its vaccine review office, will retire on October 31. Krause, who serves as the vaccine team’s deputy director, will leave in November.

Peter Marks, director of the agency’s Center for Biologics Evaluation and Research, said Gruber’s departure is a “huge loss” and Krause was highly committed during the COVID-19 pandemic. He said that a search for the next vaccine office director “will begin imminently.” He did not speculate on why both team members have suddenly decided to step down at around the same time. An FDA spokesperson said that the regulator is “confident in the expertise and ability of our staff to continue our critical public health work, including evaluating COVID-19 vaccines.”

Acting FDA Commissioner Janet Woodcock expressed her confidence in the team that will remain in place under the leadership of Marks, who will step in as acting director for the vaccine office. As she said, “We have put together a plan that will allow us to continue prioritizing science, while meeting timelines that are important to ensuring the end of this devastating pandemic.”

The surprise development comes at a critical time for the FDA’s vaccine review team. The FDA is now deciding whether to authorize a potential third Pfizer shot for most Americans and could soon evaluate the use of coronavirus vaccines in children. The White House said that the U.S. will start administering boosters the week of September 20, a debated decision that preceded the FDA’s completion of its own review. The Biden administration announcement puts pressure on the FDA to clear boosters in time for the planned rollout.

Senior health officials claim that there is a waning immune response in vaccinated individuals and that boosting antibody levels by means of a third shot could strengthen protection. Both FDA and CDC leaders agreed to the idea of a White House announcement in August.

Pfizer has filed for approval of a booster, but the review of that application will now happen without Gruber or Krause, a loss for the agency’s efforts to rapidly assess the submitted data. According to Luciana Borio, a former chief scientist with the agency, the FDA “is losing two giants who helped bring us many safe and effective vaccines over decades of public service.” Gruber and Krause were important players in establishing the guidelines Pfizer, Moderna and Johnson & Johnson had to abide by to win emergency clearance of each of their vaccines.

According to BioPharma Dive, “Reviewing each shot under the emergency pathway — a regulatory tool reserved for a public health crisis — required the FDA to move as quickly as possible to get the vaccines to market without compromising its standards. Gruber and Krause were also vocal participants in the public meetings to review the emergency applications from each developer, chiming in to settle scientific disputes among outside reviewers and clarify the agency’s position. Their sudden and near concurrent departures could raise questions about the impact political pressure, now spanning two administrations, is having on the agency.”

Former BARDA director Rick Bright said, “These two are the leaders for Biologic (vaccine) review in the US. They have a great team, but these two are the true leaders of CBER. A huge global loss if they both leave. Dr. Gruber is much more than the Director. She is a global leader. Visionary mastermind behind global clinical regulatory science for flu, Ebola, Mers, Zika, Sars-cov-2, many others.”