US Health Secretary Robert F Kennedy Jr came under sharp criticism during a Senate Finance Committee hearing on Thursday, where lawmakers from both parties questioned his handling of vaccines, the turmoil at the Centers for Disease Control and Prevention (CDC), and his fitness to lead the nation’s public health agencies.

The session, which lasted more than three hours, saw Democratic senators openly call for Kennedy’s resignation. Senator Ron Wyden of Oregon accused him of showing a “reckless disregard for science and the truth,” while Raphael Warnock labeled him a “hazard to the health of the American people.”

Lawmakers pressed Kennedy over his mixed messaging on vaccines, including his past remarks casting doubt on the effectiveness of Covid-19 inoculations, despite his recent expressions of support for President Donald Trump’s “Operation Warp Speed.”

Republican senators who had backed Kennedy’s confirmation, such as Bill Cassidy of Louisiana and John Barrasso of Wyoming, also voiced frustration with his contradictory statements.

CDC leadership turmoil

The hearing came amid growing unrest inside the CDC. Last week, Kennedy dismissed newly appointed director Susan Monarez, sparking a legal challenge. Several senior officials resigned soon after, citing disillusionment with his vaccine policies.

Earlier this year, Kennedy also removed all 17 members of the CDC’s vaccine advisory panel, despite assurances during his confirmation hearing that no such overhaul would occur. Many of his replacements have long histories of vaccine skepticism.

“These actions are destabilizing the nation’s leading health agency at a time when public trust is already fragile,” said Senator Elizabeth Warren, who confronted Kennedy over his shifting descriptions of Monarez, once praised as “unimpeachable” and later denounced as untrustworthy.

Kennedy’s lack of medical credentials raises alarm

Concerns over Kennedy’s qualifications have also fueled criticism, as Kennedy does not hold a degree in medicine, health sciences, or public health. His background is in law and environmental advocacy, and he previously led the environmental group Waterkeeper Alliance.

Public health experts argue that this lack of medical expertise undermines his credibility. More than 17,000 physicians and 75 Nobel laureates opposed his nomination earlier this year, warning that his history of promoting vaccine misinformation would “put the public’s health in jeopardy.”

Public health consequences

The policy changes under Kennedy are already being felt nationwide. The United States is experiencing its worst measles outbreak since 2000, with more than 800 reported cases and three deaths as of April 2025. Vaccination rates for measles, mumps, and rubella have fallen below the 95% threshold required for herd immunity.

Meanwhile, the Food and Drug Administration has limited Covid-19 vaccine eligibility to people over 65 and those with underlying conditions, effectively halting widespread access. Experts fear that such restrictions could leave children and younger adults vulnerable during future outbreaks.

Kennedy has also cut hundreds of millions of dollars in mRNA vaccine research contracts and halted National Institutes of Health programs aimed at preparing for future pandemics. Critics warn these decisions risk setting back progress against infectious diseases.

Experts warn of a growing crisis

Public health leaders say Kennedy’s policies threaten to undo decades of work in disease prevention. The American Public Health Association has called his approach “a danger to the public’s health,” while over 1,000 current and former HHS employees have signed letters urging his resignation.

As pressure mounts from lawmakers, health professionals, and the public, Kennedy continues to defend his record. “We are the sickest country in the world,” he told senators. “That’s why we need change at the CDC.”