The director of the U.S. Centers for Disease Control and Prevention (CDC) is resigning.

Dr. Rochelle Walensky is stepping down at the end of June, the director told President Joe Biden in a letter, the CDC said on May 5.

Walensky, 54, did not cite a specific reason, but said she believes the CDC is in a better position now than when she assumed the post on Jan. 20, 2021, the same day Biden was inaugurated.

“The end of the COVID-19 public health emergency marks a tremendous transition for our country, for public health, and in my tenure as CDC Director. I took on this role, at your request, with the goal of leaving behind the dark days of the pandemic and moving CDC – and public health – forward into a much better and more trusted place,” Walensky told Biden. “In the process, we saved and improved lives and protected the country and the world from the greatest infectious disease threat we have seen in over 100 years.”

Biden said in a statement that Walensky “has saved lives with her steadfast and unwavering focus on the health of every American” and that “we have all benefited from her service and dedication to public health, and I wish her the best in the next chapter.”

Under Walensky, the CDC has made multiple false statements on COVID-19, including exaggerating the effectiveness of COVID-19 vaccines. Polls show that Americans’ trust in the CDC has fallen during the pandemic.

Before becoming the CDC’s director, Walensky was chief of the Division of Infectious Diseases at Massachusetts General Hospital and a professor of medicine at the Harvard Medical School.

The position of CDC director does not require Senate confirmation, unlike similar positions such as the head of the U.S. Food and Drug Administration. White House officials have not identified potential replacements as of yet.

This is a developing story that will be updated.