David Kessler, top health official for Covid vaccines, to leave Biden administration

David Kessler, a key official in the Biden administration's Covid vaccine and treatment efforts, is stepping down from his role as chief science officer, the Department of Health and Human Services announced Friday.

Since January 2021, Kessler has played a leading role in the development and roll out Covid vaccines. He took the reins of the Trump-era initiative dubbed Operation Warp Speed to accelerate vaccine and treatment development.

Kessler, 71, is the latest Covid response official to step down at President Joe Biden's two-year mark in office. In December, Anthony Fauci stepped down as director of the National Institute of Allergy and Infectious Diseases and as Biden’s chief medical adviser.

On Friday, Health and Human Services Secretary Xavier Becerra lauded Kessler for his contributions to the agency's Covid response, saying he "helped save lives."

“For decades, Dr. Kessler has worked tirelessly to address our nation’s most challenging public health issues, and his work during the COVID-19 pandemic has been no different," Becerra said. "Dr. Kessler’s contributions to our COVID-19 response have helped save lives. I am grateful for the wisdom he has shared with us and wish him the best in his future endeavors.”

NBC News has reached out to Kessler for comment.

After the 2020 election, Biden's transition team tapped Kessler to co-chair an advisory board to combat the coronavirus pandemic that included former U.S. surgeon general Vivek Murthy, who is now back in his former post.

The Biden administration and health officials have had to combat misinformation and conspiracy theories about Covid vaccines during their rollout. The latest figures from the Centers for Disease Control and Prevention show that 78.8% of U.S. adults have completed their primary series of Covid vaccines.

Kessler's earlier government service included Food and Drug Administration commissioner from 1990 to 1997. During that time he oversaw the agency's response to the HIV/AIDS crisis and was later known for efforts to regulate the tobacco industry.