Former CDC Director Raises Alarm on Childhood Vaccine Schedule Changes

On Wednesday, Susan Monarez, PhD, former director of the CDC, appeared before a panel of the Senate, testifying that proposed changes to the childhood vaccine schedule—including measles, chickenpox, hepatitis B, and COVID-19 shots—lack scientific backing. She was joined by Debra Houry, MD, MPH, former chief medical officer of the CDC, who is 1 of 3 senior officials at the CDC who resigned last month.

The hearing spotlighted turmoil within the CDC, particularly surrounding changes to vaccine policy and the dismissal of Monarez. Lawmakers pressed the witnesses on the absence of scientific evidence supporting proposed revisions to the childhood vaccine schedule. Both Monarez and Houry testified that they had not seen any supporting data and expressed serious concerns about the integrity of the decision-making process.

A central focus was the role of HHS Secretary Robert F. Kennedy Jr, who was alleged to have pressured Monarez to approve recommendations without evidence and to have replaced all members of the Advisory Committee on Immunization Practices (ACIP). Both witnesses highlighted transparency issues, censorship, and the sidelining of CDC experts from key policy discussions. Questions also arose over the qualifications of the newly appointed ACIP members and the reliability of their recommendations.

Moreover, both Monarez and Houry warned that politicizing vaccine policy could have dangerous consequences for public health. Weakening or undermining established recommendations, they argued, risks fueling vaccine hesitancy and triggering new outbreaks of preventable diseases.

Changes to Hepatitis B Vaccine Recommendations

During the hearing, the hepatitis B vaccine emerged as a central point of debate, with Monarez and Houry underscoring its historical success and the risks of altering current policy. Following the introduction of the vaccine in 1982, reported cases of hepatitis B fell from a peak of more than 26,000 in 1985 (with an estimated 172,700 actual cases) to fewer than 3000 reported cases in 2014—a nearly 90% decline.¹ Universal infant vaccination, recommended since 1991 and later expanded to all children and adolescents up to age 18, has been pivotal in driving these declines.

Concerns were raised that the newly reconstituted ACIP, under Kennedy’s leadership, may push to delay the birth dose until age 4—a move experts warned could undermine decades of progress and leave infants vulnerable. Monarez and Houry described how traditional CDC expert review processes were bypassed, with pressure to use questionable evidence, fueling concerns that political influence rather than science is guiding the recommendations. Both emphasized they had seen no new evidence supporting such a change and cautioned that weakening the policy would jeopardize infant health and public trust in vaccines.

“Vaccines are safe; they're lifesaving, and I would encourage any parent who is concerned about whether or not their child should get a vaccine to talk to their pediatrician to understand the benefits of these lifesaving medical products and to make the best decision that they can to make sure that their children remain healthy and happy and can go to school and be safe,” said Monarez.

Trust in Public Health Institutions

The hearing devoted significant attention to the issue of trust in public health institutions, underscoring how political interference and a lack of transparency have eroded confidence in agencies like the CDC. Monarez, Houry, and senators pointed to the COVID-19 pandemic as a turning point, when shifting guidance, school closures, and perceived politicization deepened public skepticism. The experts stressed that restoring trust requires a recommitment to scientific integrity, ensuring that policy decisions are guided by evidence rather than ideology or political agendas. They warned that sidelining career scientists in favor of political appointees undermines institutional knowledge and damages the credibility of public health recommendations. The erosion of trust, they noted, has direct consequences—lower vaccine uptake, confusion among parents and providers, and worse outcomes for children’s health.

Calls for “radical transparency” and accountability highlighted the urgent need for open communication, clear evidence-based recommendations, and the protection of scientific independence to rebuild public confidence.

“I certainly think openness to change and supporting the administration's priorities are important,” said Houry. “I was selected to be the transition lead for the agency because I was known as somebody that could embrace both administrations and help implement policies. That was my goal. I'm the last, or I was the last career [professional] left in the office of the director.”

Reference

1. ACIP evidence to recommendations for a universal hepatitis B (HepB) vaccination strategy in adults. CDC. September 5, 2024. Accessed September 17, 2025. https://www.cdc.gov/acip/evidence-to-recommendations/hepb-adults-etr.html