Kennedy said former CDC Director Susan Monarez lied in her op-ed published in the Wall Street Journal on Thursday morning, in which she detailed the pressure she faced from Kennedy.

Monarez wrote that in that meeting, she was "told to preapprove the recommendations of a vaccine advisory panel newly filled with people who have publicly expressed antivaccine rhetoric ... It is imperative that the panel’s recommendations aren’t rubber-stamped but instead are rigorously and scientifically reviewed before being accepted or rejected."

"Did you in fact, do what Director Monarez said you did, which is tell her just go along with vaccine recommendations even if she didn't think such recommendations aligned with scientific evidence?" Democratic Sen. Ron Wyden asked Kennedy.

"No, I did not say that to her, and I never had a private meeting with her," Kennedy said.

"So she's lying today to the American people in the Wall Street Journal?" the senator asked.

"Yes, sir," Kennedy said.

Monarez's lawyer pushed back on Kennedy's claims, calling them "false" and "patently ridiculous."

"Dr. Monarez stands by what she said in her op-ed in The Wall Street Journal, would repeat it all under oath and continues to support the vision she outlined at her confirmation hearing that science will control her decisions," her lawyers, Mark Zaid and Abbe Lowell, said in a statement.

Kennedy said that he received latest numbers from the CDC that 76.4% of Americans now have a chronic disease.

"This is stunning … This is a national security issue," he said. "When my uncle was president, we spent zero on chronic disease. We [have now] spent $1.3 trillion."

Kennedy claimed this is why peopled needed to be fired at the CDC, saying they "didn't do their job" to keep Americans healthy.

Before facing questions from lawmakers, Kennedy took a moment in his opening statement to address recent turmoil at the CDC.

"These changes were absolutely necessary adjustments to restore the agency to its role as the world's gold standard public health agency with the central mission of protecting Americans from infectious disease," Kennedy said.

He said the agency needed "new blood" and criticized its response to the COVID-19 pandemic. Many public health experts argue that politics and social resistance hampered the CDC's efforts to quell the pandemic and save lives.

Last week, Susan Monarez was ousted from her role as CDC director over her resistance to changes on COVID vaccine policy. Four top CDC officials then resigned in protest.

Kennedy's opening statement was momentarily interrupted by a protester.

“You’re killing millions of people!” the person said before being removed.