What Is the Advisory Committee on Immunization Practices (ACIP)?

Established in 1964, the ACIP is a federal advisory committee chartered to make recommendations on the use of safe and effective vaccines in the US. The ACIP develops recommendations for the Director of the Centers for Disease Control and Prevention (CDC). If these recommendations are adopted and published in the appropriate Immunization Schedule, they facilitate access to vaccines without cost-sharing across most insurance programs.

Recent Member and Operational Changes

In June, the Secretary of the Department of Health and Human Services (HHS) Robert F. Kennedy Jr announced the removal of all 17 sitting members of the committee, replacing the prior experts with new voting members. The Committee’s new membership met three times in 2025 and developed recommendations on the use of a respiratory syncytial virus (RSV) pediatric monoclonal antibody and narrowed recommendations for thimerosal-containing influenza vaccines, COVID-19, and measles, mumps, rubella, and varicella (MMRV).

In August, liaison members, who are representatives of key vaccinating provider groups such as the American Academy of Pediatrics (AAP) and American College of Obstetricians and Gynecologists, were notified that they would no longer be permitted to participate in work group (WG) discussions. Historically, these liaisons have participated in all ACIP WGs, providing expertise, experience, and insights critical for discussions relating to specific vaccine use and implementation.

Looking Ahead: 2026 ACIP Areas of Focus and Operating Changes

During the December ACIP meeting, the Committee announced several potential areas of focus for future meetings, which can inform key priorities and possible areas for changes in 2026. In addition, there have been notable changes in how the ACIP operated in 2025 relative to historical norms which could impact how these topics are reviewed at coming meetings.

Potential 2026 ACIP Focus Areas:

• Human papillomavirus (HPV), RSV, and influenza vaccines and vaccines used during pregnancy: Updated Terms of Reference for these WGs are expected to be published in the near future signaling topics under consideration.
• Vaccine adjuvants and components: Presentations on vaccine adjuvants, particularly aluminum salts, raised several questions for consideration, including whether different formulations or schedules should be preferred based on vaccine ingredients. It was also announced that the Committee is considering developing a WG dedicated to examining the effects of vaccine adjuvants. Historically, it has been the role of the Food and Drug Administration (FDA) to evaluate the safety of vaccine composition and individual components or ingredients, including those used as adjuvants, which have not required distinct approval. Further, significant safety signals have not been associated with adjuvants or components for this to be under consideration by the ACIP or even the FDA.
• Cumulative effects of the child and adolescent immunization schedule: Presentations at the December meeting introduced the topic of the cumulative effects of vaccines administered to children and adolescents.
• Aligning US vaccine recommendations with best practices from peer countries: Some December meeting presentations compared US vaccine recommendations to those of perceived peer nations (e.g., Japan, Germany, Denmark). As evidenced by a recent presidential memorandum, there may be increased momentum from agencies to align recommendations with those of such countries in the near term.

Deviations from Historical Operating Norms:

1. Evidence Review

Historically, the ACIP has used Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) or Evidence to Recommendations (EtR) frameworks to systematically review data for a specific product or product class to inform clear and concise evidence-based recommendation development. Vaccine stakeholders, including AAP, have voiced concerns that the Committee is not using clear or systematic evidence review methodologies.

At the December meeting, the data presented to inform the Committee’s decision-making for HepB vaccine birth dose recommendations did not use a meta-analysis or scientific evaluation framework. Voting members Drs. Cody Meissner, Joseph Hibbeln, and Raymond Pollack, along with liaison members, voiced concerns about the lack of assessment or evaluation criteria to inform review and subsequent evidence-based recommendations. They noted that data intended to demonstrate potential HepB vaccine safety signals to demonstrate potential lack of safety failed to do so. Specifically, the Committee’s proposed recommendation language suggested the first hepatitis B (HepB) dose be administered at two months of age; however, no data were presented to demonstrate the clinical rationale for this decision.

Ultimately, the ACIP voted to suggest that the first dose of HepB vaccine be administered at two months of age. Under previous ACIP processes, additional critical aspects of a vaccine recommendation would have been included in an EtR (e.g., implementation, cost effectiveness) to understand the impact of the recommendation on the US population.

Typically, CDC subject matter experts who are involved in WG activities lead presentations related to their expertise for the ACIP public meetings (e.g., burden of disease, vaccine coverage rates, EtR presentations). At the December meeting, presentations were led by voting members, CDC contractors, or external participants, such as Aaron Siri, a vaccine injury litigation attorney and former personal lawyer to Secretary Kennedy. Siri led a presentation on the evolution of the childhood and adolescent vaccine schedule and its compatibility with those of other peer, developed nations.

Despite a disjointed December ACIP meeting, the Committee’s vote to recommend use of the HepB birth dose based on individual-based decision-making rather than the previous universal recommendation is not anticipated to cause significant access issues to families that chose to vaccinate using the birth dose.  Based on coverage statutes and updates from Centers for Medicare and Medicaid Services officials, this recommendation is treated the same as a shared clinical decision-making recommendation, which requires coverage without cost sharing for all commercially insured and Vaccines for Children (VFC)-eligible children.

Moving forward, the ACIP may continue to review vaccine products without a clear, evidenced-based review system for new and existing products. This may require stakeholders to shift how they prepare for potential ACIP recommendation scenarios for specific products.

2. Procedural Approaches and Working Norms

The December meeting included several procedural inconsistencies. While WG activities have historically occurred in closed-door settings, WG membership and general updates on activities have been public. Since the reconstitution of the ACIP, there have been very few details related to which WGs are active, how frequently they are meeting, and who is participating. Liaison members have repeatedly requested these details. Despite comments from ACIP Vice Chair Dr. Robert Malone suggesting that WG details were forthcoming, many specifics, especially WG membership, remain unavailable.

Additionally, the HepB voting language changed several times over the course of the two days, making it challenging for the public and voting members to keep track of what was actually being voted on. Drs. Meissner and Hibbeln repeatedly noted concerns about the ability to digest the information presented in the context of frequently changing language. Ultimately these concerns led to a vote to delay the HepB vote by a day for the Committee to reassess and reformulate the recommendation. In the end, both HepB votes passed.

Given the uncertainty about future transparency into WG membership and potential voting language, stakeholders should prepare for various potential scenarios that could be reviewed by the Committee.

3. Lack of Clarity on Remit and Responsibilities

Throughout the meeting there were also several instances of confusion from ACIP members about the role, responsibility, and impact of the Committee recommendations.

Over the last few ACIP meetings, there have been multiple instances of confusion about the coverage impact of VFC resolutions. For example, at the September meeting, the Committee voted against the VFC resolution for MMRV vaccines, only to revote the next day to approve the resolution. Similarly, at the December meeting several voting members appeared to not understand the remit ACIP recommendations have on various markets and that a VFC resolution provides critical access to nearly 50% of children in the US. Different outcomes for ACIP recommendation and VFC resolution votes could lead to disparities in coverage between public and private markets and perpetuate preexisting differences in disease outcomes among these groups.

Another instance of voting member confusion arose in the context of a vote to recommend serological testing to inform subsequent doses of HepB vaccines. Historically, ACIP recommendations have been solely for the use of vaccines and not for other medical products such as testing or diagnostics. Liaison members noted concerns about the implementation of this recommendation since it does not fall within the scope of ACIP recommendations and therefore the ACIP likely cannot require payers to cover serology testing without cost sharing.

As the ACIP continues to assess pediatric vaccine recommendations, it will also be critical to continue to monitor what, if any, differences there are between future recommendation and VFC resolution votes for access to pediatric vaccines through VFC compared to commercially insured children. This is particularly important given the Committee’s historic lack of clarity about impact of VFC resolutions and ACIP recommendations across markets.

Conclusion

While there has been significant uncertainty around the priorities and processes of the newly constituted ACIP to this point, discussions and presentations from the December ACIP meeting point to topics the Committee plans to explore in coming months. The Committee’s intended focus on influenza vaccines, HPV vaccines, maternal vaccination, adjuvants and contaminants, the cumulative effects of the childhood and adolescent immunization schedule, and schedule alignment with peer countries highlights the potential for meaningful changes to the US vaccine landscape in 2026.

Such changes could have significant implications for provider behavior, vaccine coverage, patient access, public trust, vaccine uptake, vaccine supply, and the vaccine supply chain. It’s critical that stakeholders monitor additional changes in the federal vaccine regulatory and advisory environment to prepare for shifts in vaccine evidence requirements and effectively strategize to mitigate potential risks, potentially with the collaborative efforts of emerging guideline development groups and vaccine coalitions.

To learn about how Avalere Health can assist you as you navigate this landscape, connect with us.