WATCH: ‘We were lied to about everything’ around COVID, RFK Jr. says

Health and Human Services Secretary Robert F. Kennedy Jr. said Thursday that the country’s response to the COVID-19 pandemic was politicized, and alleged that the federal government had lied to the American public about the effectiveness of vaccines and masks.

READ MORE: 4 major moments from RFK Jr.’s contentious hearing with senators

In a hearing about President Donald Trump’s health care agenda, Sen. John Cornyn, R-Texas, asked Kennedy whether he believed “COVID-19 was politicized.”

“The whole process was politicized, senator. I mean, we were lied to about everything,” Kennedy responded.

Kennedy claimed the government, including the Centers for Disease Control and Prevention, lied about “natural immunity,” that vaccines would prevent transmission and infection, and the “science behind cloth masks.”

Many of those allegations are false or misleading. It’s not clear what Kennedy was referencing when he mentioned “natural immunity,” but there is no evidence that any significant group of people were immune to COVID before either contracting the disease or receiving a vaccination.

In early 2021, soon after the initial COVID vaccines had received emergency use authorization by the government, then-CDC Director Rochelle Walensky said that “vaccinated people do not carry the virus, don’t get sick.” She also said data showed vaccinated people didn’t transmit COVID. But the CDC’s official guidance at the time was that vaccines only “reduce the risk of people spreading COVID-19.”

The federal government’s mask guidance changed dramatically over the course of the pandemic, much of which occurred during Trump’s first term. The CDC regularly advised people to wear the most effective masks available, including N95 and KN95 respirators, surgical masks or homemade cloth masks, which the agency said were “inferior” but “a suitable option for community use when medical masks are unavailable.”

Kennedy appeared before the Senate Committee on Finance a day after more than 20 medical societies and organizations called for his resignation. They cited “repeated efforts to undermine science and public health,” most recently the firing of CDC Director Susan Monarez over vaccine science and the resulting resignations of other leaders at the organization.

During his tenure, the health secretary and former anti-vaccine advocate has narrowed long-standing U.S. vaccine recommendations. He’s also replaced a key panel of medical experts with his hand-picked candidates ahead of the start of the respiratory virus season in the United States.