Two Republican senators -- both doctors -- sidestepped questions from ABC News about whether they still have confidence in RFK Jr. to continue leading HHS in the wake of the hearing.

When asked if RFK Jr. assuaged his concerns or if the HHS secretary should resign, Sen. Bill Cassidy of Louisiana referred to the questions he asked at the hearing.

Cassidy pointedly questioned the secretary on his COVID-19 vaccine policies.

GOP Sen. John Barrasso of Wyoming, the number two Republican in the Senate and a doctor as well, also avoided questions about confidence in RFK Jr.

"I have confidence in what the president of the United States is doing and I would not second guess it," he told ABC News.

During the hearing, Sen. Roger Marshall, a Republican from Kansas, pointed to a sign that said "76 JABS" noting that is how many vaccines children in the U.S. receive by age 18.

Children and teens may receive multiple vaccines before adulthood; these are often broken up into multiple doses. These multiple doses do not overwhelm a baby's immune system, the CDC says.

Vaccines are given early in life because that is the time when people are especially susceptible to diseases.

Some babies may also receive vaccines as a combined shot that reduces the number of needles they get at one time.

-ABC News' Youri Benadjaoud and Dr. Jade Cobern

The hearing has ended after nearly three hours. At many times contentious, Kennedy was grilled on everything from vaccine availability to his staffing shakeups at the CDC. Several Republicans on the panel expressed concern on vaccines, while Democrats accused Kennedy of breaking pledges he made during his confirmation hearing back in January.

Kennedy is currently not testifying under oath after Sen. Crapo denied a request to do so.

At the beginning of the hearing, Sen. Wyden asked that Kennedy be formally sworn in as a witness.

"I will personally object and will reject your request," Crapo said. "We will treat this witness as we treat all of the other administration witnesses who come before us."