Director of the premier public health organization in the United States, Rochelle Walenskyannounced that she would step down from her position at the end of June, without explaining exactly the reasons for her resignation, referring only to a “favorable” transition period, thanks to the lifting of the health emergency associated with COVID-19.

Walensky, 54, was director of the Centers for Disease Control and Prevention (CDC) for about two years. He was instrumental in implementing President Joe Biden’s pandemic response policy when the CDC launched an unprecedented vaccination campaign. He also made very regular appearances on television educating American citizens about prevention and explaining the measures being taken.

The “ending of the health emergency” for the US on May 11 “marks an extraordinary transition for our country, for public health, and for my role as director of the CDC,” she wrote in a letter to Biden. “I have never been so proud of anything else in my professional career that I have achieved,” she added, referring to her work at the CDC.

The former Harvard professor of medicine and head of infectious diseases at a major hospital in Massachusetts, however, has come under fire during the pandemic largely because of the “chaotic” way information is passed from the CDC at times.

“She led a complex organization at the forefront of a once-in-a-generation pandemic,” Biden said in a brief statement, praising Walensky’s “honesty and integrity.”

It has not yet been announced who will replace Valensky at the CDC.