A Senate health committee hearing Wednesday spotlighted a sharp rift over the vaccine-policy agenda pushed by Robert F. Kennedy Jr. Susan Monarez, the ousted director of the Centers for Disease Control and Prevention, testified that she was fired by Health and Human Services Secretary Robert F. Kennedy Jr. and President Donald Trump after clashing with the administration’s plans for vaccine guidance.
Monarez said Kennedy pressed her to approve, sight unseen, the new vaccine recommendations that would be issued by the Advisory Committee on Immunization Practices, or ACIP, which Kennedy has staffed with experts he selected. She testified that, during a contentious meeting before her firing, he asked her to approve the forthcoming ACIP recommendations and to dismiss career CDC vaccine scientists. The panel is now staffed by Kennedy-picked experts, according to Monarez. The meeting she referenced is set to unfold over the next two days, with ACIP panels discussing potential changes to the childhood vaccine schedule and the federal guidance for Covid-19, hepatitis B, and measles-mumps-rubella shots.
During the hearing, Republican senators sought to challenge Monarez’s credibility, but the committee chair, Sen. Bill Cassidy (R-La.), pushed back against what he called potential threats to a scientifically grounded vaccine schedule. Cassidy, a physician by training, warned against “unjustified changes” to the childhood vaccine schedule, with a particular emphasis on the hepatitis B shot.
At the heart of the debate is the hepatitis B vaccine, which is given at birth in many places. Rand Paul (R-Ky.) suggested delaying the vaccine for newborns unless maternal hepatitis B status is known, arguing that the early timing may be unnecessary in some cases. Cassidy, in a closing line of the hearing, provided a counterpoint: he noted that untreated hepatitis B infection at birth carries a greater than 90 percent risk of chronic infection, and he recalled that the United States once saw roughly 20,000 babies infected each year before the birth-dose vaccine became standard in the early 1990s. Now, he said, the number is far lower—“less than 20”—and he framed the milestone as an achievement in public health.
Cassidy also underscored that the CDC does not mandate the hepatitis B vaccine; it requires coverage by insurers when parents choose to vaccinate. “Now that we’ve controlled [hepatitis B], do we let the genie out of the bottle?” he asked, indicating concerns that removing the newborn recommendation could affect insurance coverage for the shot.
The encounter did not produce widespread calls for Kennedy’s resignation, but it did reflect growing GOP unease with his overhaul of vaccine policy and the appointment of an ACIP lineup aligned with his MAHA agenda. Sen. John Barrasso (R-Wyo.) has pressed Kennedy on the value of vaccines in prior hearings, and Politico has reported a broader ambivalence among several Republican colleagues. Still, Kennedy retains allies beyond Cassidy and Sen. Susan Collins (R-Maine), and the hearing covered how the administration intends to proceed with the two-day ACIP sessions.
As the two-day ACIP meetings proceed, lawmakers will be watching whether any substantive shifts to the newborn hepatitis B schedule or to the broader vaccine guidance emerge, and whether any additional testimony or investigations into the health agency’s leadership will follow. The hearings highlight the ongoing tension between political leadership and scientific agencies over how vaccines are recommended, funded, and implemented in the United States, a debate with potential implications for public health policy and health coverage in the years ahead.