Dr. Stephen M. Hahn, who became Commissioner for the Food and Drug Administration just weeks before the coronavirus pandemic began, resigned on Wednesday when President Biden’s administration began.

Dr. Janet Woodcock, longtime director of the FDA’s Center for Drug Evaluation and Review, will serve as acting commissioner, according to an agency official.

From May, Dr. Woodcock has been tasked with Operation Warp Speed, the previous government’s program to accelerate vaccine and treatment development for the coronavirus.

She has been with the FDA since 1986 and has served in a number of key roles including Chief Medical Officer and Assistant Commissioner.

The Biden administration has not yet appointed a permanent commissioner, but Dr. Woodcock is one of the contemplated candidates, according to several advisors to the new president’s transition team. Dr. Amy Abernethy, Deputy Chief Commissioner, is also being considered, as is Dr. Joshua Sharfstein, a former agency officer who is the vice dean of public health practice and community involvement at Johns Hopkins University.

The resignation of Dr. Hahn was expected to be part of the routine departure of senior political figures that comes with the assumption of office of a new administration. In a farewell message to FDA staff on Wednesday, he wrote: “As a nation and as a health agency, we have faced major challenges and turbulent times over the past year, particularly due to the Covid-19 pandemic. Throughout all of this, FDA staff have been instrumental in responding to the disease with very real scientific advances like the approval of the first non-prescription OTC [over the counter] Covid test, the approval and approval of an antiviral agent, and the first two FDA-approved Covid-19 vaccines. “

Dr. Hahn received considerable criticism in the course of the pandemic. He has been accused of bowing to political pressure from President Trump and the White House to issue emergency clearances for unproven treatments such as hydroxychloroquine that did not provide evidence of their effectiveness. For the past few months, he has led reviews of the first vaccine against the virus, Pfizer and Moderna products.

In the past, 72-year-old Dr. Woodcock among other presidential administrations in the race for the top position of the FDA. It was first introduced by Dr. David Kessler, the former FDA commissioner who was named chief science officer for the Biden Administration’s vaccination efforts, no longer referred to as Operation Warp Speed, to the FDA’s Drugs Division.

The Biden administration did not specify when an FDA commissioner would be appointed.