The Advisory Committee on Immunization Practices (ACIP) just kicked off its two-day meeting on Wednesday, aiming to shape federal vaccine policy. Normally, the committee meets three times a year without much attention, but this time is different.
GOP Senator Bill Cassidy and Democratic Senator Patty Murray have both called for the meeting to be delayed, expressing concerns over the new committee members appointed by Health Secretary Robert F. Kennedy Jr. They argued that many of the new picks “lack experience studying new technologies such as mRNA vaccines,” with Cassidy specifically warning that some “may even have a preconceived bias against them.”
Let’s take a closer look at what the committee does, who its controversial new members are, and what this could mean for federal policy going forward.
What does the ACIP do?
The Advisory Committee on Immunization Practices (ACIP) is a group of medical and public health experts who play a critical role in shaping U.S. vaccine policy across both the public and private sectors. Its recommendations to the Centers for Disease Control form the basis for the country’s official immunization guidelines, which determine who should receive which vaccines, at what ages, how often, and under what conditions.
These guidelines are then adopted not only by public health programs such as Vaccines for Children (VFC) and Medicaid, but also by private healthcare providers and insurance companies, ensuring a unified approach to vaccination standards nationwide.
So when Robert F. Kennedy Jr. stated in May that the CDC planned to sideline ACIP in deciding COVID-19 vaccine guidance for healthy kids and pregnant women, it sparked concern among many. The committee doesn’t just offer advice — it grounds its decisions in analysis of vaccine safety, effectiveness, and disease trends.
ACIP’s guidance also evolves with the science: As new research emerges, new diseases appear, or new vaccines are approved, the committee revisits that information and revises its recommendations accordingly.
Who are the controversial new members of ACIP?
In June 2025, RFK Jr. fired all 17 members of the ACIP and brought in eight new ones, many of whom have limited experience with vaccines or have questioned their safety and effectiveness. Here’s a quick rundown of these new members’ backgrounds:
Vicky Pebsworth
This nurse, health care administrator, and health policy analyst has previously served as a voting member of the FDA’s Vaccines and Related Biological Products Advisory Committee. Pebsworth’s interest in vaccine safety is rooted in personal experience: She believes her son developed long-term health issues following routine childhood immunizations.
Pebsworth is also a polarizing figure: Supporters view her as a strong advocate for informed consent, while critics worry her views could lend credibility to vaccine skepticism in policymaking circles. She currently serves on the board of the National Vaccine Information Center, a group widely described by public health experts as anti-vaccine.
Robert Malone
An American physician and biochemist who conducted early research on mRNA technology in the late 1980s, Robert Malone, MD, participated in work that helped lay the foundation for later vaccine development, though he has claimed he hasn’t received proper credit.
While he was not involved in creating the mRNA-based COVID-19 vaccines used by Pfizer or Moderna, Malone has since positioned himself as a prominent critic of them. In a video circulated online in 2023, he claimed that these vaccines could “cause permanent damage in children’s critical organs” and provide no benefit to them — statements that have been widely dismissed by public health experts as unsubstantiated and misleading.
Malone has also promoted ivermectin, an antiparasitic drug, as a treatment for COVID-19 — despite multiple rigorous studies showing it offers no meaningful benefit. He continues to appear in media and online platforms that often amplify vaccine skepticism and pandemic-related misinformation.
Martin Kulldorff
Kulldorff, PhD, is an epidemiologist who became a prominent figure during the Covid-19 pandemic for downplaying its severity and advocating against widespread lockdowns. He argued that lockdowns should be limited to protecting vulnerable populations, such as the elderly and those with underlying health conditions, rather than imposing blanket restrictions.
Kulldorff’s stance on the pandemic appears to have remained consistent. As recently as 2022, he was fired from his position at Harvard University after reportedly refusing the COVID-19 vaccine, despite the institution’s mandates requiring vaccination for faculty and staff. His refusal, along with his public stance on COVID-19 policy, fueled further controversy and debate within the academic and medical communities.
Cody Meissner
Cody Meissner, MD, has prior experience serving on the ACIP, having been a member until 2012. While some of his colleagues took more cautious or controversial stances on the COVID-19 vaccines, Meissner was quick to emphasize their importance from the start.
In 2021, he notably stated, “It’s important that the main message we transmit is that we’ve got to get everyone two doses.” However, Meissner has also expressed opposition to mask mandates for children and has voiced skepticism about the necessity of repeated Covid-19 booster shots for younger populations, reflecting a more nuanced view on pandemic response measures.
Joseph Hibbeln
A respected figure in nutritional neuroscience, Joseph Hibbeln is known for his research on omega-3 fatty acids and mental health. His appointment to ACIP certainly brings a unique perspective, combining nutrition and brain science with vaccine policy.
While Hibbeln’s background in federal research and public health is notable, his focus on nutrition represents a departure from the committee’s traditional emphasis on immunology and infectious disease, raising questions about how his expertise will influence vaccine policy.
Retsef Levi
A professor of operations management at the Massachusetts Institute of Technology (MIT) in Cambridge, Levi has published several papers expressing skepticism about mRNA vaccines, including those used for COVID-19. In a post on X, he wrote, “The evidence is mounting and indisputable that mRNA vaccines cause serious harm, including death, especially among young people. We have to stop giving them immediately!”
James Pagano
This former emergency physician in Los Angeles also served as the medical director at Garfield Medical Center in Monterey Park, California.
While Robert F. Kennedy Jr. has described Pagano as a “strong advocate for evidence-based medicine,” his background does not seem to include formal credentials in immunology or vaccine science, areas traditionally central to vaccine policy and decision-making.
Michael Ross
Michael Ross, MD, previously served as a presidential appointee on a CDC committee focused on preventing breast and cervical cancer. However, his LinkedIn profile lists specialties including “Contact lenses, International Business, Healthcare and Pharmaceutical Executive Management, and Pharmaceutical Consulting” — areas of focus outside the traditional medical or public health realms.
Ross is currently an obstetrician and the chief medical officer at Manta Pharma, a Maryland-based company specializing in implantable devices. He has also served as a board member and adviser for nearly a dozen pharmaceutical and medical device companies, including LarreaRX, a natural supplement manufacturer.
What are the wider implications of the ACIP’s latest meeting?
Infectious disease experts are sounding the alarm over what’s at stake. At its latest meeting, the newly restructured ACIP will vote on recommendations for several major vaccines — including COVID-19, HPV, meningococcal disease, and RSV. The outcome could reshape both childhood and adult immunization schedules.
The panel is also expected to consider the future of thimerosal, a preservative still used in some flu shots. Public health officials worry that if the new members move to scale back vaccine recommendations or reduce dosing schedules, it could mark a significant shift in how the U.S. approaches immunization.
And it’s not just about guidance — it’s about access. As Dr. Paul Offit, a pediatric infectious disease specialist at the Children’s Hospital of Philadelphia, told Nature, insurers aren’t required to cover vaccines that fall outside ACIP recommendations. Even for those willing to pay out of pocket, availability may shrink if those vaccines lose the committee’s backing.
With so much riding on ACIP’s guidance, this week’s meeting could shape vaccine access, trust, and policy for years to come.
