Less than a month after taking office, Susan Monarez, director of the U.S. Centers for Disease Control and Prevention (CDC), was fired on Wednesday.

"Susan Monarez is no longer director of the Centers for Disease Control and Prevention. We thank her for her dedicated service to the American people," the Department of Health and Human Services (HHS), which oversees the CDC, said in a post on X, without providing further explanation.

Sworn in as the CDC chief on July 31, Monarez has since become the shortest-serving CDC director in the agency's history.

A few hours after the HHS announcement, Monarez's legal team issued a statement that she had neither resigned nor been fired.

Her lawyers accused HHS Secretary Robert F. Kennedy Jr. of "weaponizing public health for political gain" and said that by purging health officials from the government, he had put "millions of American lives at risk."

Kennedy has made sweeping changes to vaccine policies, including withdrawing federal recommendations for COVID-19 shots for pregnant women and healthy children in May and firing all members of the CDC's expert vaccine advisory panel in June and replacing them with handpicked advisers, including fellow anti-vaccine activists.

Shortly after the statement was issued, the White House officially fired Monarez.

"Since Susan Monarez refused to resign despite informing HHS leadership of her intent to do so, the White House has terminated Monarez from her position with the CDC," White House spokesman Kush Desai said in a statement.

The Washington Post, citing two people familiar with the situation, reported that Monarez was "pressed for days" by Kennedy, administration lawyers and other officials over whether she would support rescinding certain approvals for coronavirus vaccines.

"Kennedy, who has a long history of anti-vaccine advocacy, and other officials questioned Monarez on Monday on whether she was aligned with the administration's efforts to change vaccine policy, the people said," the report noted.

Several senior officials at the CDC also resigned on Wednesday. According to U.S. media reports, the resignations were related to dissatisfaction with vaccine policies, alleged misinformation and politicization of public health.