We first covered AAP et al. v. Kennedy et al. on this blog . We covered it again . This is a follow-up to what has happened since the decision was issued.
If you have been following the ongoing battle over the direction of childhood vaccine policy in the United States, you may already know that things have moved fast and often in surprising directions. This post is a follow-up on the lawsuit formally known as , filed in federal court in Massachusetts. Since we last checked in, a federal judge issued a sweeping ruling that temporarily reversed many of the vaccine policy changes made by Health and Human Services (HHS) Secretary Robert F. Kennedy Jr., and the government has responded with a maneuver that legal experts are watching very carefully.
Let us go back to the beginning.
How the Lawsuit Came to Be
To understand why this lawsuit was filed, you first need to know about the , or ACIP. Think of ACIP as a standing board of scientific reviewers, made up of independent doctors, researchers, and public health experts, and then tell the Centers for Disease Control and Prevention (CDC) which vaccines Americans should receive, at what age, and in what doses. When the CDC Director accepts those recommendations and formally adopts them, they become the official U.S. immunization schedule. That schedule, in turn, determines what vaccines health insurance plans must cover at no cost to patients, and which vaccines children in low-income families can get for free through a federal program called .
In May 2025, Secretary Kennedy issued what he called a “” ordering the CDC to remove its recommendation that healthy children and pregnant women receive the COVID-19 vaccine. He did this without consulting ACIP, even though consulting ACIP is exactly how those decisions are supposed to be made under federal law. Kennedy had actually not to do anything that would discourage people from getting vaccinated, a promise he appeared to break within months of taking office.
Then, in June 2025, Kennedy went a step further. He of ACIP in a surprise announcement published in The Wall Street Journal, replacing the entire panel with 15 new members of his own choosing. He said the old committee had been “plagued with persistent conflicts of interest” and had acted as a “rubber stamp” for new vaccines. Medical organizations and public health professionals immediately raised alarms, pointing out that this happened against the backdrop of a , with over 1,000 reported cases by May 2025, the vast majority in unvaccinated people.
On July 7, 2025, four prominent medical groups responded by filing a lawsuit in federal court in Boston: the , the , the , and the . They were later joined by additional organizations and individual plaintiffs, including pregnant physicians who wanted the COVID-19 vaccine but felt uncertain about their options. The case was assigned first to Judge William Young and later transferred to Judge Brian E. Murphy.
The lawsuit accused the administration of violating two key federal laws: the (APA), which is the law that requires federal agencies to follow orderly, evidence-based processes when they change rules and policies (and not just act on a whim), and the (FACA), which requires advisory committees like ACIP to be made up of members with a genuine balance of relevant expertise rather than being stacked to reach a pre-decided conclusion.
The Case Expands
Throughout the second half of 2025, the case grew considerably. In January 2026, acting , moving several vaccines from the “recommended for everyone” category to a “shared clinical decision-making” category. To understand what that downgrade means in practice, let’s look at an example: imagine your child’s pediatrician used to recommend a flu shot during every fall visit automatically. Under the new policy, she would instead have to sit down with you and say, “Well, whether your child gets a flu shot is sort of up to you.” For vaccines for which the scientific evidence clearly supports universal use, that kind of shift can dramatically reduce uptake, especially in busy clinic settings or among families who already have doubts.
The new schedule memo was issued without meaningful ACIP involvement and provided no scientific explanation for the changes. The plaintiffs updated their lawsuit to include this memo, and on January 6, 2026, Judge Murphy denied the government’s motion to dismiss the case, finding that the medical organizations had standing (meaning they had a genuine legal right to bring this lawsuit because they suffered real harm, such as having to divert staff time and resources to advising confused members about the new conflicting policies) and that the claims were legally solid enough to move forward.
What the Judge Decided
On March 16, 2026, after hearings in February and March, Judge Murphy issued a , which is a court order that temporarily blocks something from going into effect while a case is still being decided. Think of it like a referee calling a timeout while the officials review the play. The final decision has not been made yet, but things are paused until the rules can be properly examined.
The ruling was sweeping. The judge issued three specific “stays,” which are official pauses on three separate actions:
First, he blocked the January 2026 CDC memo that had cut the childhood vaccine schedule from 17 routine recommendations down to 11. The childhood immunization schedule effectively reverted to its , which means the vaccines that had been downgraded or removed are once again standard recommendations.
Second, he froze the appointments of 13 of the 15 new ACIP members that Kennedy had chosen. The judge was pointed in his language, noting that only about six of those fifteen members had any meaningful experience in vaccines, which is, after all, the entire subject matter of the committee. He described the others as “distinctly unqualified.” Because nearly the entire committee’s membership was frozen, ACIP effectively could not function. A meeting scheduled for March 18 and 19 was canceled.
Third, the judge stayed all the votes that the reconstituted ACIP had taken during 2025. Those included votes in June 2025 on flu vaccines and the vaccine ingredient thimerosal (), in September 2025 on COVID-19 vaccines, and in December 2025 on hepatitis B vaccines for newborns.
Judge Murphy’s core legal finding was straightforward: Congress specifically required the CDC Director to get input from ACIP before changing immunization schedules, and multiple federal laws tie insurance coverage, Medicaid benefits, the Vaccines for Children program, and other protections directly to ACIP’s official recommendations. The CDC cannot simply bypass its own legally mandated advisory process because the Secretary wants to move quickly. As the judge , “there is a method to how decisions about vaccine recommendations have historically been made, a method scientific in nature and codified into law through procedural requirements.”
He also found that the reconstitution of ACIP likely violated FACA because the law requires advisory committees to have a “fair balance” of expertise and viewpoints. Appointing members specifically because they agree with the Secretary’s existing position on vaccines, rather than because of their scientific qualifications, does not meet that standard.
The is that routine childhood vaccines, which had been downgraded, are now standard recommendations. Insurance coverage at no out-of-pocket cost remains in place because that coverage is tied by federal law to ACIP recommendations. Major insurers had already committed to honoring the pre-change schedule through the end of 2026. Clinicians who had been worried about legal liability for following scientific consensus rather than the contested CDC recommendations also got some relief.
The Government’s Response: A New Playbook
The Trump administration’s initial reaction to the ruling was defiant. HHS spokesman Andrew Nixon wrote on social media that the administration “looked forward to this judge’s decision being overturned.” However, two weeks later, the administration still had not taken the formal legal step of appealing the ruling, which observers found notable, given how quickly it had appealed other unfavorable decisions. Reuters that senior officials were weighing their options, including appealing, accepting the ruling, rebuilding ACIP to meet the judge’s requirements, or some combination of the three. The hesitation reportedly reflects a political calculation heading toward midterm elections: Kennedy’s supporters want a fight, but broader public support for the administration’s vaccine agenda is limited.
Rather than immediately appealing, the administration pursued a different strategy. On April 7 through 10, 2026, HHS published a in the Federal Register. A charter is the governing document that spells out a committee’s purpose, who can sit on it, and how it operates. ACIP charters are required by law to be renewed every two years, and past renewals have typically been minor administrative updates. This renewal was anything but minor.
The New ACIP Charter
The new charter expands who qualifies to serve on ACIP. While the previous charter emphasized expertise in immunization practices, public health, clinical vaccine use, and vaccine research, the new version adds expertise in fields like toxicology (the study of how substances can be harmful to the body), pediatric neurodevelopment (the study of how children’s nervous systems and brains develop), and knowledge about “recovery from serious vaccine injuries.” It also broadens eligibility to anyone “knowledgeable in the field of medicine,” which legal experts have noted is a very wide umbrella, likely designed to make it harder for a court to argue that future appointees are unqualified.
The new charter also added four organizations as “liaison members,” groups that can participate in committee discussions. These include and the , both of which have well-documented histories of opposing routine vaccination. The Infectious Diseases Society of America “another alarming action by Secretary Kennedy” that would further dismantle vaccine infrastructure and spread confusion. Dr. Demetre Daskalakis, a former CDC official, told STAT News that “the new charter shifts ACIP into an organization focused more on risk and has provided a platform for organizations that have historically been opponents of vaccination.”
The change to meeting frequency is also notable: where the old charter said ACIP would meet at least three times a year (giving the schedule some predictability and independence), the new charter says meetings will be called at the discretion of the designated federal official, in consultation with the chair. That is a shift from a structured scientific calendar to something that can be turned on or off by political leadership.
HHS insists the changes are routine. “The ACIP charter renewal and its publication are routine statutory requirements and do not signal any broader policy shift,” . Legal experts, however, disagree that the changes are routine. Dorit Reiss, , noted that the weakened expertise requirement appears designed to make it harder for future judges to demand the kind of scientific credentials that Judge Murphy insisted upon. According to the , the updated charter could allow Kennedy to rebuild the committee with some or all of the same members previously frozen by the court, without even needing to appeal the ruling formally.
Children’s Health Defense Jumps In
A separate actor in this story deserves mention: Children’s Health Defense (CHD), before becoming HHS Secretary. CHD tried to intervene in the AAP lawsuit in February 2026, arguing that the court needed to also hear from families of children allegedly harmed by vaccines under the old schedule. Judge Murphy denied that request in a single sentence, which CHD’s attorney described as “troubling.” CHD announced on March 25, 2026, that to the First Circuit Court of Appeals, which is the federal appeals court based in Boston that covers Massachusetts. CHD’s attorney, Rick Jaffe, wrote publicly that he expects this case to reach the Supreme Court “sooner than you might think.”
Where Things Could Go From Here
With a preliminary injunction in place, the underlying case still needs to go to trial. The court has only said that the plaintiffs are likely to succeed, not that they have definitively won. Here is a look at the different directions this could take.
The most immediate path involves appeals. The Trump administration has a 60-day window from the March 16 ruling to file a formal appeal with the First Circuit. CHD, for its part, has already filed an emergency motion asking the First Circuit to reverse Judge Murphy’s intervention denial and to suspend the preliminary injunction while the appeal proceeds. If the First Circuit sides with CHD or the administration, the vaccine schedule changes, and the frozen ACIP could potentially come back into effect while the full trial plays out.
The administration could also choose to accept the ruling on the committee removals and simply rebuild ACIP under whatever requirements the court has set out. That is exactly what the : by broadening who qualifies as an eligible member on paper, Kennedy could potentially reappoint many of the same people, arguing they now meet the new criteria. Whether a court would accept that maneuver is a genuine legal question. As the plaintiffs’ attorney Richard Hughes IV told Politico, “any legal action around the updated charter would hinge on what Kennedy does now with the ACIP.”
A third path leads to the Supreme Court. If the case works its way through the First Circuit with rulings that favor either side, the losing party will almost certainly seek further review. The Supreme Court’s current composition and its recent rulings on agency authority (most notably the longstanding rule that courts should defer to federal agencies’ interpretation of their own laws) make the ultimate legal outcome genuinely unpredictable.
Meanwhile, that whatever path the federal government chooses “will be a calculated move leading up to the midterm elections.” Vaccine policy has become deeply partisan, and both sides understand that this case is not only about public health science but also about the political limits of how far an executive-branch official can go in reshaping major national health programs without following the procedures Congress set up.
What This Means in Plain Terms
For parents trying to figure out which vaccines their children should get right now, the schedule in place before Kennedy’s changes took effect (specifically, the version from June 2024) is the one that is legally operative at this moment. Your pediatrician’s guidance and the , which the Academy published independently in January 2026 after Kennedy’s CDC diverged from scientific consensus, remain the best places to look for evidence-based information.
For clinicians: insurance coverage for the full pre-change schedule remains in place under federal law for now. The major insurers have publicly committed to covering the June 2024 schedule.
For all of us watching this unfold: the core question this case is asking is whether a cabinet secretary can bypass the expert review process that Congress wrote into law, not just for vaccines, but as a principle of how federal agencies must operate. The outcome of AAP v. Kennedy will carry consequences well beyond this particular health debate, because the administrative rules at stake govern how science is incorporated into federal policy across many domains.
The case has not ended. If anything, the publication of a newly revised ACIP charter just days ago signals that the administration is seeking to achieve its goals through different channels rather than backing down. The referees have called a timeout, but both teams are very much still on the field.