“Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), submitted her resignation to the Biden administration Friday, The Associated Press reported.

Her last day will be June 30. It is unclear who will lead the agency after her departure.

Walensky did not cite a specific reason for her departure, other than that the waning of the COVID-19 pandemic was a good time to make a transition.

However, The Washington Post reported that White House Chief of Staff Jeff Zients ‘had developed frustrations with Walensky’ and met with her earlier this year ‘to discuss her future in the administration.’”