Top Biden administration COVID-19 adviser David Kessler, who played a substantial role in the distribution of vaccines and treatments in recent years, has decided to step down from his position at the end of January, as The Hill reports.

The imminent departure of Kessler, 71, comes on the heels of a December decision from Anthony Fauci to step down from his post as director of the National Institute of Allergy and Infectious Diseases and as chief medical adviser to the White House, as NBC News noted.

COVID adviser to depart

Starting in January of 2021, Kessler has been engaged in the development and eventual roll-out of COVID-19 vaccines and treatments, working to help the administration achieve President Joe Biden's declared goal of delivering 100 million shots in his first 100 days in the Oval Office.

Later into his tenure as a top Biden COVID-19 adviser, Kessler played a pivotal role in the campaigns to increase booster shot uptake and expand the availability of testing and treatment across the country, according to Politico.

With an altered pandemic landscape now at play, the federal government has shifted its priorities with regard to the COVID-19 response, and updated vaccines targeting newer viral variants have not seen the widespread acceptance among the population that the original shots enjoyed.

After Congress refused administration requests for additional funding for the large-scale COVID-19 response seen in prior years, and with state and local governments seeming to move away from pandemic footing, the Biden administration has begun preparations for a wind-down of the federal emergency response likely to occur later in 2023.

Administration officials react

Kessler's decision to step down from that role prompted words of praise and tribute from Department of Health and Human Services Secretary Xavier Becerra, according to The Hill.

“Whether he was leading our effort to develop and distribute safe and effective COVID-19 vaccines and treatments or sharing his perspective during daily strategy sessions and data deliberations, Dr. Kessler's contributions to our COVID-19 response have helped save lives,” Becerra said.

The HHS secretary added. “I am grateful for the wisdom he has shared with us and wish him the best in his future endeavors.”

White House chief of staff Ron Klain was similarly effusive in his reaction to the news, tweeting, “There has been no more valued and trusted wise advisor to the @POTUS on scientific and medical matters than Dr. Kessler. He will be GREATLY missed.”

Kevin Munoz, White House deputy press secretary, joined those honoring the departing adviser, saying, “Dr. Kessler has been an incredible leader, securing the American people ready access to cutting-edge vaccines and treatments. His leadership has saved so many American lives and he will be dearly missed.”

New vaccine concerns emerge

Just as administration officials are praising the vaccine successes seen during Kessler's tenure, however, potentially alarming news emerged about the new bivalent COVID-19 vaccine from Pfizer, as Politico separately noted.

On Friday, the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) indicated that the Vaccine Safety Datalink had flagged what could be a link between the new shots and strokes in individuals over the age of 65.

The system reportedly “raised a question of whether” the risk of stroke was elevated in the initial 21 days following vaccination as opposed to the period of 22-44 days after injection in the impacted demographic group.

According to the statement from the agencies, “Although the totality of the data currently suggests that it is very unlikely that the signal...represents a true clinical risk, we believe it is important to share this information with the public, as we have in the past, when one of our safety monitoring systems detects a signal.”

Surveillance data was said to have met criteria pointing to the need for further review of whether the Pfizer shot produced a higher danger of ischemic stroke in those 65 and up, though the drugmaker itself said “there is no evidence to conclude that ischemic stroke is associated with the use” of the vaccines.

The CDC and FDA both declared that, despite the potential safety signal, they would continue to recommend uptake of the shots across population sectors.

Even so, House Energy and Commerce Committee chair Rep. Cathy McMorris Rodgers (R-WA) said that her panel would seek testimony on the issue and added, “[t]hese agencies must rapidly investigate, in an open and transparent manner, whether or not the vaccine may have contributed to the reported strokes. If there's one lesson that the CDC and FDA should have taken away from the pandemic, it's the importance of providing honest, clear, precise, and timely information to the American people about the potential risks and benefits of COVID-19 interventions, including vaccination.”