Emergent BioSolutions CEO Robert Kramer announced Tuesday that he is retiring effective immediately.

Haywood Miller, managing director of Berkeley Research Group, was named interim CEO as the company searches for a permanent successor. Kramer, who is also stepping down from the company’s board of directors, will serve as an advisor to Emergent until August 1.

Kramer, who has been with the company since 1998 and briefly stepped down as CEO in 2010, commended Emergent for its efforts to develop treatments for diseases like smallpox, COVID-19 and Ebola during his tenure.

“It has been a privilege to lead this dedicated and passionate team. I leave Emergent with confidence in the strong culture of quality and compliance, embedded core values, and focus on the mission, which will ensure Emergent’s continued success and impact on its patients, customers, and communities,” he said in a statement. “Emergent no doubt will further shape and support governments’ preparedness and response efforts to help keep people safe, and I am proud and grateful to have been a part of that journey.”

While he cited the pandemic as a time when Emergent stepped up to meet the moment, the company was embroiled in a vaccine manufacturing controversy that captured headlines in the spring of 2021.

Johnson & Johnson announced in late March 2021 that a Baltimore facility run by Emergent ruined a batch of millions of COVID-19 vaccines. The ensuing scandal focused on quality control issues at the plant, questions over whether Kramer and top leaders at Emergent knew about the longstanding manufacturing concerns and an investor lawsuit.

This fiasco culminated with the federal government canceling its more than $600 million deal with Emergent near the end of 2021. A congressional investigation into the matter resulted in a report released last year that estimated Emergent dumped more than 500 million tainted doses of vaccines produced for J&J and AstraZeneca.

Still, despite the COVID vaccine controversy, Emergent ended 2022 on an upswing thanks to its work addressing the opioid epidemic.

In December, the Food and Drug Administration granted Emergent Biosolutions priority review for its over-the-counter Narcan nasal spray and ultimately approved the product in late March.