During a Senate hearing on Wednesday, Health Secretary Robert F. Kennedy Jr. faced rigorous scrutiny from several U.S. senators, with discussions primarily centered on the government’s handling of the recent measles outbreak and the proliferation of vaccine misinformation.

In his opening statements to the Senate Finance Committee, Senator Ron Wyden sharply criticized Kennedy’s communication regarding vaccines. Wyden stated, “Robert Kennedy has used his significant platform to instill doubt in parents about vaccines and their healthcare providers,” before further asserting, “The secretary has sidestepped the issue without addressing the critical message: vaccines save lives in America.”

The session saw heightened tensions when the conversation shifted to the measles outbreak. Wyden confronted Kennedy about his longstanding views on vaccines, challenging his attempts to distance himself from the outbreak during his appearances on Capitol Hill.

Public health experts have contended that Kennedy did not adequately advocate for vaccination. Instead, they argue, he focused on unverified treatments, such as steroids, as the virus spread across state borders.

In response, Kennedy defended the U.S. response to the outbreak, claiming it was more effective than any other nation’s efforts. He pointed out that both Mexico and Canada reported higher numbers of measles cases.

“I had nothing to do with the measles outbreak here,” Kennedy insisted. “We have managed to contain our outbreak better than any country in the world.”

The US recorded 2,288 measles cases last year – the highest number since the disease was declared eliminated in the country 25 years ago. Another 1,748 cases have already been reported this year so far, raising concerns among experts that the US could lose its elimination status.

Wyden also pressed Kennedy on whether he would release his written agreements with pharmaceutical companies the following day.

“No, I will not,” Kennedy responded. “And I can explain why. Those agreements contain proprietary information and trade secrets.”

Senator Michael Bennet questioned Kennedy about changes to vaccine recommendations, pointing out that 2025 saw the highest number of childhood flu deaths in modern American history.

“I assume you no longer believe that the flu vaccine is destroying children’s brains, that there’s zero evidence that the flu vaccine prevents any hospitalizations or any deaths, because today, you’re here agreeing that the vast majority of kids that died from the flu were people without vaccines,” Bennet said.

Kennedy replied: “We’re making sure that we follow the science.”

Bennet then asked whether Kennedy was “taking the position that the measles vaccine is vital to keeping American children healthy in this country”.

“That’s my position,” Kennedy responded. “We promote the measles vaccine.”

Senator Ben Ray Luján also accused Kennedy of “pushing vaccine misinformation” that predated his tenure and pressed him to explain how he would reduce the number of measles cases and improve the MMR vaccination rate.

“We promote the MMR. We advise every child to get the MMR,” Kennedy said, seemingly a strong pivot from his previous mixed messaging.

In recent months, the Trump administration has appeared to somewhat step back from its earlier position that vaccines pose a major public health risk. This shift has coincided with declining poll numbers for Republicans before the November midterm elections, along with ongoing criticism from the medical community.

The Republican senator Bill Cassidy, a strong supporter of vaccines, notably did not bring up the topic during his questioning of Kennedy. Cassidy had supported Kennedy’s confirmation after receiving assurances that federal vaccine guidelines would be upheld, assurances that were ultimately not fulfilled.

Cassidy is facing a challenging primary election in Louisiana next month, where Donald Trump has endorsed one of his opponents in a rare effort to unseat a member of his own party.

Kennedy also repeated his assertion that the administration is not reducing Medicaid funding. He cited a congressional budget office projection showing spending on the program rising from $668bn in 2025 to $981bn in 2036, representing a 47% increase.

However, the increase would have been even larger if congressional Republicans had not passed the One Big Beautiful Bill Act last summer. According to a budget for 2027 the White House proposed earlier this month, the Department of Health and Human Services (HHS) could see its budget cut by more than $15bn, 12% less compared with this year.

Artificial intelligence (AI) in healthcare was another topic raised during the hearing. Senator Maria Cantwell asked about the use of AI in potentially cutting or denying Medicare claims.

Kennedy responded that the technology was “supposed to allow us to detect fraud” but acknowledged there were “probably kinks in the system”, adding that HHS would work to “try to straighten that out”. He had noted earlier that some states were expanding AI use in diagnostics, billing and management, describing these applications as “resourceful and imaginative”.

Fourteen months after Kennedy took office as health secretary, the nation’s leading public health agency continues to face significant disruption.

About 80% of senior leadership roles at the Centers for Disease Control and Prevention (CDC) remain unfilled, leaving no permanent leadership to guide policies affecting millions of Americans. No one is in place to coordinate the agency’s day-to-day work fighting infectious disease, combatting heart conditions or screening for cancer.

According to current and former senior CDC officials, bureaucratic delays and paperwork backlogs have slowed productivity in several areas. Disruptions in data collection have left the agency struggling to operate effectively.