What You Should Know About This Week's Vaccine Meeting

The Advisory Committee for Immunization Practices (ACIP) met at the headquarters of the Centers for Disease Control and Prevention (CDC) in Atlanta this week for the first time since Health Secretary Robert F. Kennedy Jr. fired all 17 sitting members earlier this month and replaced them with eight of his own. This sudden shakeup has many in public health concerned, given Kennedy’s vocal skepticism of vaccine safety.  

The agenda included discussions about recommendations and schedules for COVID; hepatitis B (HepB); RSV; measles, mumps, rubella, and varicella (MMRV); and HPV vaccines; among others. To help make sense of the meeting, Jodie Guest, PhD, professor of epidemiology at Rollins, provides her reactions to topics the committee discussed and what this group’s actions could mean for Americans’ health. 

Watch the meeting here.

What impact do ACIP's decisions have on immunizations in the U.S.?

The ACIP’s decisions directly shape the U.S. immunization schedule and recommendations. Once ACIP votes on a vaccine, whether by age group, dose number, or at-risk population, those guidelines are typically adopted by CDC, become part of the Vaccines for Children (VFC) program, and are followed by state health departments, insurance companies, and clinicians. ACIP’s guidance thus drives both policy and practice nationwide.

In this week’s ACIP meeting, the new chair discussed the hepatitis B vaccine, which is given at birth. Why is this vaccine given at birth?

The newborn dose of hepatitis B (HepB) vaccine is recommended to:

• Protect infants early, before any potential exposure
• Prevent perinatal transmission from infected mothers, which can leave infants chronically infected with lifelong risks
• Increase vaccination coverage, since hospital birth provides an ideal location to ensure at least one dose is received

Dr. Kulldorff reaffirmed at the ACIP meeting on Wednesday that the HepB birth dose is aligned with evidence-based, long-standing practice to safeguard infants from day one.

What other comments were made in this week’s ACIP meeting that may signal a change in future vaccine recommendations?  

Two notable headlines from Wednesday's ACIP meeting were:

• ACIP announced new work groups to review existing schedules and “long-approved vaccines” (including the HepB  birth dose and MMRV), as well as the cumulative effect of multiple vaccines.
• A presentation on thimerosal by Lyn Redwood—a former anti-vaccine group leader—suggests ACIP may reevaluate preservatives in vaccines.

These items signal that ACIP may initiate more in-depth reviews of established vaccines and ingredients, potentially leading to updated recommendations or guidelines. 

Any changes ACIP makes can directly impact what vaccines are required for school entry, how pediatricians follow immunization schedules, and how public health agencies communicate safety and effectiveness. Even small shifts in recommendations can have a ripple effect on trust, access, and uptake nationwide.

While it’s critical to remain open to new data and responsive to emerging issues, revisiting long-settled science—such as the safety of vaccine schedules or ingredients—can cause harm by lending credibility to disinformation and fueling public confusion. Doing so risks undermining decades of public health progress built on sound, evidence-based science.

The committee voted to recommend Merck's new RSV vaccine for infants today. Why is this important for public health and how soon would this recommendation go into effect?

ACIP voted today to recommend Merck’s monoclonal antibody for infants under 8 months entering their first RSV season. This is a major public health advance, as RSV is a leading cause of hospitalization and death in infants. ENFLONSIA has demonstrated ~60% reduction in RSV infections requiring medical attention and ~84% lowered hospitalization risk. The recommendation goes into effect once CDC leadership signs off—typically the CDC director or, currently, Secretary Kennedy, and will be implemented through the Vaccines for Children program beginning this summer, in time for the 2025–26 RSV season.

Another big development from today was the ACIP's vote to recommend flu vaccines without thimerosal for all age groups. How will this impact Americans? What about people in other countries?

This effectively discourages use of multi-dose vials containing this preservative which is less than 5% of flu vaccines in the U.S. 

For U.S. residents, most flu shots are already preservative free, so this will shift demand away from multi-dose vials and reduce vaccine availability in settings relying on bulk doses—like some clinics and pharmacies—possibly raising costs and causing local supply gaps. 

On an international level, countries that depend on multi-dose vials—especially low- and middle-income nations—may face higher expenses or logistical challenges. Multi-dose packaging helps lower costs and simplifies distribution in resource-limited areas, so removing it could reduce access globally. 

The vote to remove thimerosal from vaccines relies on outdated evidence and disregards decades of research affirming its safety. It's also largely symbolic. Thimerosal is currently only used in a small fraction of multi-dose flu vaccine vials in the U.S. Rather than improving public confidence, this decision risks increasing confusion and mistrust which may, unfortunately, be the point. 

According to The New York Times,  Kennedy told the international organization, Gavi, that the U.S. is going to cease financial support for “the group’s work purchasing vaccines for children in poor countries." How will this decision impact the children in these countries?

Gavi leverages U.S. contributions (about $300 million per year) to provide vital coverage across 78 countries, preventing nearly 19 million deaths. The sudden withdrawal could disrupt bulk-purchasing arrangements, worsen vaccine shortages, and delay immunizations, resulting in increased child mortality from preventable diseases. It is anticipated that more than 1 million preventable deaths could occur if funding lapses.