In a major shake-up at the US Food and Drug Administration (FDA), top regulators left on Friday – including Tracy Beth Høeg, the acting drug chief, who says she was fired, and Katherine Szarama, the acting vaccines chief who has only been in the position for days. Jim Traficant, the chief of staff, has also been ousted.

The FDA now has no permanent commissioner or deputy commissioner and no permanent leaders of two major centers, after the resignation of Marty Makary on Tuesday and other high-profile departures.

According to an email obtained by the Guardian, FDA staff only received official word on Friday afternoon that Makary is leaving and Kyle Diamantas, previously the top food regulator, will temporarily lead the agency as acting commissioner – though they had clues from President Donald Trump’s social media posts and the reported removal of Makary’s photo from the lobby of FDA headquarters.

The departure of Makary and several key allies at FDA signifies a potential new direction for the agency, which has been rocked by controversial decisions on vaccines, rare disease medications, staff layoffs and low morale.

“I was fired,” Høeg wrote on X on Friday night, noting that she had served exactly six months as head of the Center for Drug Evaluation and Research (CDER) – though she didn’t mention she served as acting, not permanent, director of the center.

Høeg told the New York Times and other outlets that she was fired from the agency after she declined to resign.

Before overseeing the nation’s drug regulation center, Høeg was an adviser to Makary, and she focused on gathering reports of adverse vaccine reactions and attempting to align the US childhood vaccine schedule with that of Denmark, where Høeg is a dual citizen and received her degree in epidemiology. A sports medicine physician, Høeg rose to national prominence by casting doubt on the safety and necessity of Covid vaccines, and she had no apparent experience in drug regulation.

Høeg was the fifth leader of the center in a year, after high-profile departures of leaders such as George Tidmarsh and Richard Pazdur.

Michael Davis, CDER’s deputy director, will now serve as acting director, according to STAT News.

Szarama took over as acting director of the Center for Biologics Evaluation and Research (CBER) after the departure of another highly controversial figure, Vinay Prasad, last month. But Szarama, who was in the position for 10 days and had not even had time to update her LinkedIn profile, is also reportedly leaving the agency. Karim Mikhail, who was CEO of the pharmaceutical company Amarin before joining FDA last year, will now temporarily head the center.

Traficant, who was chair and CEO of Citadel Sciences before joining the FDA last March, is also out.