WASHINGTON — Dr. David A. Kessler, who for the previous two years has been the behind-the-scenes pressure driving an enormous federal effort to develop and distribute coronavirus vaccines and coverings, is leaving the Biden administration — one other signal that the pandemic is not entrance and middle for the White Home.

As chief science officer for the administration’s Covid-19 response, Dr. Kessler, 71, has operated largely unseen by the general public. However his work — on points like organising mass vaccination websites, pushing for the event of antiviral medicines and distributing reformulated booster pictures — has affected the lives of tens of millions of Individuals.

“600 sixty-five million vaccines, 13 million antivirals,” Dr. Kessler mentioned in a quick interview on Friday, referring to the variety of doses that Individuals have taken since December 2020, shortly earlier than President Biden took workplace. “We did what we got down to do.”

Nonetheless, tens of millions of Individuals stay unvaccinated, and the general public has been gradual to obtain the brand new booster doses. When requested in an interview final summer season if vaccine hesitancy pissed off him, Dr. Kessler talked as an alternative in regards to the mass vaccination websites, his efforts to distribute pictures to pharmacies and nursing properties, and his work to make them accessible to kids.

“Our job was getting secure and efficient vaccines to be accessible,” he mentioned then, “and to ensure that everybody might have it, and that it was straightforward.”

Dr. Kessler’s departure indicators the top of Operation Warp Pace, which was began by the Trump administration to develop and distribute coronavirus vaccines. Though the Biden administration dropped the title, the mission of this system underneath Dr. Kessler remained the identical. Now the Biden administration is working to shift Covid vaccination from a government-run effort to at least one that will probably be dealt with by the non-public sector.

In his function, Dr. Kessler was liable for negotiating with drug firms to make sure that vaccines had been accessible to anybody who wished one — at a value for the federal government that was far decrease than what firms need to cost on the industrial market sooner or later.

On Capitol Hill, some lawmakers are already gearing up for battles with the businesses. Senator Bernie Sanders, the Vermont impartial who has twice sought the Democratic nomination for president, despatched a letter to the vaccine maker Moderna this week, warning its chief govt, “Now just isn’t the time for unacceptable company greed.”

It appears unlikely that the Biden administration will exchange Dr. Kessler. Officers say the Division of Well being and Human Companies has different docs, scientists and public well being officers with experience who will work with the White Home and personal trade on vaccine analysis and growth.

Dr. Kessler had hopes of constructing a extra everlasting infrastructure for vaccine growth and manufacturing. In late 2021, the administration introduced a plan, drafted by Dr. Kessler, to take a position billions of {dollars} to develop vaccine manufacturing capability by partnering with trade to organize for future pandemics.

“That is about assuring expanded capability towards Covid variants and in addition making ready for the subsequent pandemic,” Dr. Kessler mentioned on the time. “The objective, within the case of a future pandemic, a future virus, is to have vaccine functionality inside six to 9 months of identification of that pandemic pathogen, and to have sufficient vaccines for all Individuals.”

The plan was put aside, nonetheless, when Congress refused to present the administration any further cash to spend on vaccines. The billions the administration had hoped to spend to ramp up vaccine manufacturing capability went as an alternative to buying the up to date booster pictures now being distributed.

In Washington, Dr. Kessler could also be finest remembered for a much more public function, as commissioner of the Meals and Drug Administration in the course of the presidencies of George H.W. Bush and Invoice Clinton.

Underneath Mr. Clinton, Dr. Kessler, who has a legislation diploma from the College of Chicago in addition to a medical diploma from Harvard, took on the tobacco firms, and he later wrote a e book about it. He additionally helped velocity the event of AIDS medication.

When Mr. Biden was working for president on the top of the coronavirus pandemic, Dr. Kessler was one half of a two-person staff — the opposite half was Dr. Vivek H. Murthy, now the surgeon normal — who briefed the candidate virtually day by day on issues associated to the pandemic.

When Mr. Biden turned president, Dr. Kessler took over Operation Warp Pace and ran it alongside Gen. Gustave F. Perna, who had labored underneath President Donald J. Trump and retired in 2021.

Dr. Murthy mentioned on Friday that Dr. Kessler had been an “important counselor on a variety of strategic selections” and known as him “certainly one of my absolute favourite individuals to work with within the administration.”

Dr. Kessler mentioned that he would wrap up his work within the administration subsequent week and that he anticipated to take a while off earlier than returning to educating on the College of California, San Francisco.

Xavier Becerra, the secretary of well being and human companies, praised Dr. Kessler’s service in a press release.

“For many years, Dr. Kessler has labored tirelessly to handle our nation’s most difficult public well being points,” Mr. Becerra mentioned, “and his work in the course of the Covid-19 pandemic has been no totally different.”