The newly reconstituted Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) gathered on September 18–19, 2025 to revisit vaccine safety issues. Notably, the committee has undergone sweeping internal changes to its membership. Seventeen long-serving members have been replaced with less conflicted members by HHS secretary Robert F. Kennedy, Jr. At present, there are 12 seated voting members on the ACIP panel. Despite the shake-up, adjustments to vaccine guidance and the childhood schedule have been relatively minor.
On day one of the meeting, ACIP work groups presented their findings on childhood vaccines, specifically measles, mumps, rubella, and varicella (MMRV) and the now-controversial hepatitis B vaccine, given shortly after birth. Day two focused on COVID-19 mRNA vaccines.
On September 18, Dr. Martin Kulldorff’s work group confirmed what is already known about MMRV. Children under four years of age show a slightly higher risk for febrile seizures. The CDC’s own post-licensure data show a “small but consistent bump” in febrile seizures about 7–10 days after giving the first dose of MMRV to toddlers ages 12 to 47 months. Analyses found roughly one extra seizure per ~2,300–2,600 doses, compared with giving MMR and varicella as two separate shots. The same spike is not generally seen after the second dose for 4- to 6-year-olds, and large U.S. studies allegedly have not found a significant rise in serious hematologic events like immune thrombocytopenia (ITP).
ACIP voted to stop recommending the MMRV combo shot for children under 4 years, 8-3, with one abstention. Instead, the committee recommended for the first dose under age 4 the use of separate MMR + V unless parents specifically prefer MMRV. For the second dose at age 4–6, MMRV is “generally preferred due to similar protection with no added seizure signal.” Additionally, for children under age 4, ACIP removed MMRV from Vaccines for Children (VFC), the federal program that provides free vaccines to uninsured and underinsured children. VFC will continue to cover separate MMR + varicella doses for those ages.
As for hepatitis B, the CDC’s rapid safety reviews presented at the meeting did not identify a significant increase in neonatal harms tied to birth-dose timing, though certainty for many outcomes is low, and long-term data are sparse. Public-health groups have warned that delaying the birth dose could increase missed vaccinations and infections. (Because screening can fail, results can be wrong or unavailable at delivery, and postpartum follow-up is imperfect.) Given those reservations, most external experts urged against changing policy for now. According to ongoing CDC guidance, the prudent, evidence-based course is to keep the universal birth dose while recommending higher-quality research and clearer language for any future “shared decision” carve-outs.
However, ACIP members did discuss changing the hepatitis B birth-dose policy, considering a draft that would have delayed the first hepatitis B shot to one month of age for newborns whose mothers test hepatitis B-negative, instead of the current universal birth-dose recommendation. After debate, the vote was tabled (postponed) in an 11-1 vote, with Chair Kulldorff voting against it. The committee concurred with the current CDC recommendation for universal prenatal screening of pregnant women for hepatitis B.
On September 19, ACIP examined the uncertainties surrounding the safety of the mRNA COVID vaccines, with Dr. Robert Malone forcefully arguing that there is no evidence that the COVID vaccine prevents severe infection or provides durable protection against the disease.
There are no clearly defined by standard methods of correlates of protection for COVID; not cellular, not humoral, not neutralizing. None of those have been subjected to formal analysis to define them as a correlative protection.” He continued, “So, you really have no right to assert what your feelings or opinions are about whether or not there's a correlation between any of these outcomes, these adaptive immune responses and protection. There is no established correlative protection for COVID. Period. Full stop. And stop saying otherwise.
Drs. Wafik El-Deiry and Charlotte Kuperwasser summarized their important findings with a series of published slides. Comparing Pfizer’s Comirnaty and Moderna’s Spikevax, the El-Deiry-Kuperwasser work group raised significant concerns about risks associated with the mRNA vaccines. Among those concerns were immune-system modulation, biodistribution of vaccine components, potential “off-target” protein production, residual DNA contamination, and reported cancers.
Notably, mRNA vaccines use lipid nanoparticles (LNPs), allowing easier delivery of cargo into cells. Regarding biodistribution, the S1 subunit of the SARS-CoV-2 spike protein and/or vaccine components have been detected outside the injection site in multiple organs, including the brain (biodistribution), likely a result of the LNPs that allow more efficient penetration of cells. According to the slides, LNPs have not been adequately evaluated for safety, and there are “no safety or regulatory guidelines for LNP-enveloped DNA impurities.”
Regarding the Pfizer vaccine, tests found impurities exceeding acceptable limits — approximately 36–153 times more DNA than the usual limit for leftover DNA. They also found that some of that DNA includes SV40 “promoter/enhancer” sequences. Those are tiny control switches copied from a monkey virus, Simian Virus 40 (SV40) — short pieces of viral DNA scientists that biologists put into lab DNA to make nearby genes turn on strongly in human or animal cells. If a fragment carrying those switches lands inside a chromosome, it could, in theory, turn nearby genes on or off in potentially harmful ways. “No clinical trial was conducted on the marketed product,” the slides state.
In the case of the Moderna vaccine, leftover DNA was 112–627 times over the typical limit. Shorter fragments (“small size” fragments) in the Moderna shots may more easily slip into our own DNA (integration). “The full nucleotide sequences have not been published,” the work group noted.
According to El-Deiry and Kuperwasser, there is evidence that there are “unintended/off target proteins” that “generate an immune T cell response in humans. In addition, the “immunogenic or toxic properties of the non-spike proteins are unknown.”
“Neither Moderna or Pfizer biodistribution studies used commercial product for testing.” Neither showed “biodistribution data” that indicated “confinement to site of injection.” Alarmingly, reported
distribution included draining lymph nodes, liver, spleen, heart, brain, lungs, and blood. It was noted it that components could cross the blood brain barrier (BBB). ... COVID vaccine mRNA “has been reported to persist up to 706 days.
As a result of the ACIP committee’s discussion, members voted 12-0 to recommend COVID-19 vaccines be administered with “shared clinical decision making, for adults aged 65 and older, rather than universal recommendation.” The same was recommended for individuals aged 6 months through 64 years, with the added caveat that doctors should evaluate the risk-benefit for vaccination as being “most favorable” for those at increased risk and less favorable for those whose risk of severe illness is low.
The committee also voted 11-1 to standardize informed consent practices for COVID-19 vaccines. During the pandemic, informed consent was widely inconsistent; many vial boxes included largely blank paper inserts that directed recipients via QR code to online fact sheets, an accepted FDA practice in the case of EUA protected vaccines.
Image: Robert F. Kennedy, Jr. Credit: Gage Skidmore via Flickr, CC BY-SA 2.0.