If doctors prescribed GLP-1 agonists like Wegovy and Ozempic at current prices for every overweight American who wanted the drugs, and the federal government was helping to pay for it, "it would cost a trillion dollars per year," Kennedy said. "It would double the insurance costs for employers in this country."

The brief discussion of GLP-1 agonist costs was the only time employee benefits or employers' health coverage costs came up during the three-hour hearing.

Related: Robert F. Kennedy Jr. says Trump backs pharmacy benefit manager reform

Kennedy also expressed concerns about the effects of GLP-1 agonists on people's muscles and what happens when people start taking the drugs and then stop.

Prescription drug prices: Sen. Bernie Sanders, an independent from Vermont who caucuses with the Democrats, asked Kennedy if he would commit to using the provisions now in the Inflation Reduction Act to shape how Medicare program managers bargain with pharmaceutical manufacturers.

"Trump wants us to negotiate drug prices," Kennedy said. "I'm going to comply with the law."

Vaccines: Much of the questioning at the hearing focused on Kennedy's record of skepticism about vaccine safety.

Sen. Edward Markey, D-Mass., accused Kennedy of sending a letter to the prime minister of Samoa that disrupted a measles vaccination campaign during a 2019 measles outbreak.

Sixteen children had died from the measles, and Kennedy suggested in the letter that the children might be casualties of the vaccine, Markey said.

"You were saying that it was the fault of the vaccine rather than the absence of vaccinations that caused the outbreak," Markey said. "The death count in Samoa grew to 83, and ultimately volunteers in New Zealand sent tiny coffins to help bury the dozens of children who died. A New Zealand vaccinologist later said the impact of your role was devastating."

Sen. Bill Cassidy, R-La., the chairman of the Senate HELP Committee, and Sen. Lisa Murkowski, R-Alaska, both questioned Kennedy's past skepticism about vaccines and pressed him to support vaccines now.

Murkowski noted that Alaska is just now getting through a bout of whooping cough and is now facing a possible measles outbreak.

"We can't be going backward on our vaccinations," Murkowski said. "Please convey with a level of authority and science but also with a level of conviction and free of conflict and free of political bias that these are measures that we should be proud of as a country."

Cassidy, a liver doctor, recalled seeing a girl who barely survived an emergency liver transplant after she suffered liver failure because of hepatitis B, an illness that can be prevented with a vaccine.

That story had a happy ending, "but, as a doctor, I saw endings not so happy," Cassidy said. "I just had a friend text me about two children who died in an intensive care unit in a Baton Rouge hospital from vaccine-preventable diseases this past month."

Kennedy said in response to a question from Sen. Susan Collins, R-Maine, that he supports vaccinations and believes the polio vaccine is safe and effective.

Prospects for passage: The Senate Finance Committee held a hearing on Kennedy's nomination Wednesday, and it may hold a vote on the nomination next week, according to press reports.

The Senate HELP Committee will not hold a separate committee on the nomination.

Republicans hold 53 seats in the Senate, and Vice President JD Vance can vote to break a tie.

Although Cassidy, Murkowski and Collins all expressed concerns about Kennedy's views about vaccines during the Senate HELP Committee hearing, none seemed to be firmly opposed to voting for him.

Robert F. Kennedy Jr. appeared Thursday at a Senate HELP Committee hearing on his Health and Human Services secretary nomination. Credit: Senate HELP Committee