This updated article, about the recent decision in AAP v Kennedy to stay changes to the US vaccine schedule, was written by Dorit Rubinstein Reiss, Professor of Law at the University of California Law, San Francisco, who is a frequent contributor to this and many other websites, providing in-depth and intellectually stimulating articles about vaccines, medical issues, social policy, and the law.

Professor Reiss writes extensively about the social and legal aspects of vaccination in law journals. Reiss is also a member of the Parent Advisory Board of Voices for Vaccines. This parent-led organization supports and advocates for on-time vaccination and the reduction of vaccine-preventable diseases. She is also a member of the Vaccines Working Group on Ethics and Policy.

On March 16, 2026, Federal judge Brian E. Murphy of the federal District Court of Massachusetts stayed – put on hold – the federal government’s January 5, 2026 memo changing the childhood schedule, the membership of 13 of the Advisory Committee on Immunization Practices (ACIP) members appointed by Secretary Robert F. Kennedy Jr., and the decision of the reconstituted ACIP. 

While the decision will likely be appealed, and even if not, this is not the end of the process, only a stay until litigation is completed; this is a blow to Kennedy’s agenda to reduce vaccine uptake. Among other things, the basis for the decision is the plaintiffs’ high likelihood of winning on the merits, so the judge examined their arguments and agreed with them that, essentially, the appointment of ACIP’s members and the January memo cannot, legally, stand.

Practically, too, the meaning of the decision is that the ACIP meeting due to happen on March 18-19, 2026, is canceled (people can still meet, of course, but it won’t be ACIP) and that the January memo and prior decisions by Kennedy’s ACIP are legally on hold, which could have a practical effect. 

This explainer describes the case, the reasons for the decision, and what happens next. 

AAP v Kennedy case regarding the US vaccine schedule

American Academy of Pediatrics (AAP) v Kennedy was filed on July 5, 2025, and initially challenged the change to COVID-19 recommendations removing the recommendation of the vaccine for healthy children and pregnant women. Plaintiffs included several medical associations, led by the American Academy of Pediatrics, and individuals alleging that the changes in the schedule made access to vaccines harder. 

As events unfolded, the complaint was amended, and in its final amendment, was extended to cover the revised ACIP and the January schedule change. As a reminder, in June 2025, Robert F. Kennedy Jr. fired all ACIP experts in a paywalled op-ed in the Wall Street Journal, and replaced them with people whose main qualification (for most) appeared to be voicing criticism of COVID-19 vaccines or vaccines generally.

Then, on January 5, 2026, after attempts to do the same in December 2025, the federal government, in a memo signed by then-acting CDC director Jim O’Neill, revised the United States childhood vaccine schedule to no longer recommend six vaccines. The explanation of the change was a highly flawed memo by Drs. Tracy Beth Høeg and Martin Kuldorff, alleging that the United States should follow Denmark’s schedule, a memo that did not really address the harms this could cause, and whose reliance on Denmark’s vaccine schedule – a very different country – baffled public health experts. 

On January 7, 2026, Judge Murphy rejected the government’s motion to dismiss, finding that AAP had standing and that plaintiffs made enough arguments on the merits for the case to move forward. I summarized that decision here. 

Plaintiffs asked the judge for a preliminary injunction against ACIP’s membership, the May 2025 decision on COVID-19 vaccines in pregnancy and for healthy children, and against the January 2026 schedule change. This decision is the ruling on that. 

The judge pointed out that the plaintiffs asked both for a stay of the decision under §705 of the Administrative Procedures Act and a preliminary injunction, and that both require meeting the same four criteria. The criteria, as described by the court, are that 

“A plaintiff seeking a preliminary injunction must establish that he is likely to succeed on the merits, that he is likely to suffer irreparable harm in the absence of preliminary relief, that the balance of equities tips in his favor, and that an injunction is in the public interest.” Together Emps. v. Mass Gen. Brigham Inc., 32 F.4th 82, 85 (1st Cir. 2022) (quoting Winter v. Nat. Res. Def. Council, Inc., 555 U.S. 7, 20 (2008)).”

Likelihood of succeeding on the merits – having a good chance of winning the case – is the first and most important, but the judge discussed all of these. There is very little about a stay in my administrative law textbook, but another source explained, to my understanding, that while there is a legal difference, both have the same practical effect:

Functionally speaking, “[b]oth can have the practical effect of preventing some action before the legality of that action has been conclusively determined.”24 Id. In other words, both “halt” some action.25 See generally Note, Halting Administrative Action in the Supreme Court, 137 Harv. L. Rev. 2016, 2016 (2024). Both do so only pending the final decision on the merits. And both require application of demanding four-part tests,26 Compare Winter v. Nat. Res. Def. Council, Inc., 555 U.S. 7, 20 (2008) (four-part preliminary-injunction test), with Nken, 556 U.S. at 434 (four-part stay test). It is beyond the scope of this Essay to discuss the potential differences between these tests and the tests the Supreme Court uses. See generally Hart & Wechsler, supra note 18, at 375–77, 377 n.2, 380–381; Halting Administrative Action, supra note 25, at 2019–25. tests which have “substantial overlap.”

In practical terms, the stayed decisions and memberships remain on hold until the litigation concludes or a court of appeal overturns them. 

Standing in AAP v Kennedy

Under United States law, courts cannot issue abstract decisions. A party must show it has a stake in the case by showing it suffered injury in fact, that the government’s actions caused the injury, and that the decision will remedy that injury – that means the party has standing to bring the case. This was a serious concern for plaintiffs, since the Supreme Court, in recent years, tightened standing and made it harder to bring cases.

In his earlier decision, Judge Murphy found that AAP has standing in AAP v Kennedy because AAP has, for decades, helped its members navigate vaccine issues, and the administration’s actions made that job harder. Because its members are directly affected by facing more costs, some unrecoverable, under the new framework, and they face a risk of litigation from the changes. Judge Murphy did not address standing for the other plaintiffs. 

In this decision, Judge Murphy repeated these points. He also concluded that the decision is “final agency action” with practical effect (you cannot challenge things that are not final agency action, since they are assumed not to have direct effect, and the government tried to argue that these are recommendations without such effect) for two reasons, one of which I think is much weaker than the other.

The first was that he concluded that “the CDC’s vaccine schedule sets the liability regime for healthcare providers.” This refers to the argument that shared clinical decision-making vaccines are not protected from liability because only “routine” vaccines are. I addressed this in more detail here, and this is a summary of my points. This argument has some basis. But it also has a counter, and at any rate, the change to the schedule does not automatically change liability. HHS will have to act to remove vaccines from the Vaccine Injury Compensation Program, and at this point, it has not started this process, and said it will not. So, this is a potential legal effect, but not a very strong one in the sense that it is not immediate and depends on other things happening.

More strongly, the judge reminded us that ACIP recommendations determine insurance coverage, and the changes make insurance coverage, at best, uncertain. It also affects the authority of pharmacists in many states to give vaccines. 

In that sense, the change of schedule has legal effect and is a final agency action. 

The judge also rejected the government’s argument that the decision is not reviewable, pointing out that Congress required ACIP’s involvement in vaccine recommendations in multiple statutes – the CDC Director or Secretary cannot just ignore those legal requirements. In addition, CDC’s own guidance requires that ACIP have a role in recommendations – this suggests the CDC itself interpreted the law to require it, until now. 

While judicial review does not apply to actions “committed to agency discretion,” the judge correctly pointed out that this does not mean courts don’t get to review decisions that involve discretion generally. In fact, “the Supreme Court has interpreted this exception “quite narrowly, restricting it to those rare circumstances where the relevant statute is drawn so that a court would have no meaningful standard against which to judge the agency’s exercise of discretion.” Dep’t of Com. v. New York, 588 U.S. 752, 772 (2019).”

There are no cases that applied this exception to judicial review to “the kind of regulatory power at issue in this case,” and the judge refused to do so.

The Federal Advisory Committee Act and ACIP

The composition of ACIP was addressed under the Federal Advisory Committee Act (FACA), created to reduce the number of federal advisory committees and to ensure that those that do exist are neutral and transparent. More specifically, the plaintiffs challenged that the new ACIP’s membership did not fill the requirement in FACA that committees have “balanced membership.”

On this, the court found additional reason for standing, since “FACA’s “‘fairly balanced’ requirement was designed to ensure that persons or groups directly affected by the work of a particular advisory committee would have some representation on the committee,” and, therefore, when that “requirement is ignored, persons having a direct interest in the committee’s purpose suffer injury-in-fact sufficient to confer standing to sue.” [citing long list of mostly lower-courts decisions] (note: the Supreme Court rarely takes up administrative law cases about procedural issues. So often, the jurisprudence on these issues comes from lower courts). 

Since the plaintiffs, “comprised of professional medical organizations and individual patients, clearly have ‘a direct interest in [ACIP’s] purpose,’”  they clearly have standing here, said the judge. The judge found that the Kennedy ACIP’s membership is not balanced towards fulfilling the ACIP’s role. Although “many of the ACIP members have extensive expertise in their chosen fields,” to qualify, they need “professional or personal qualifications and experience relevant to the functions and tasks to be performed by the committee.”

ACIP’s charter determines that those members should have expertise in “the fields of immunization practices and public health, have expertise in the use of vaccines and other immunobiologic agents in clinical practice or preventive medicine, have expertise with clinical or laboratory vaccine research, or have expertise in assessment of vaccine efficacy and safety.”

The judge pointed out that “of the fifteen members currently on ACIP, even under the most generous reading, only six appear to have any meaningful experience in vaccines—the very focus of ACIP.” (Note: the judge addressed only the thirteen members before the last two appointments in any depth, since those were the ones described in the filings before the hearings).

The court concluded that Drs. Hilary Blackburn, Evelyn Griffith, Joseph Hibbeln, Kirk Milhoan, James Pagano, and Raymond Pollak “appear to lack any expertise or professional qualifications related to vaccines or immunization as required by ACIP’s Charter.” (though they may have other expertise).

Drs. Retsef Levi, Robert Malone, and Catherine Stein may “have some experience arguably relevant to ACIP’s function, appear to lack the qualifications and experience to constitute expertise in vaccines and immunization.”

The judge examines their qualifications in detail in the footnotes. In his post criticizing the decision, Dr. Malone complains about the court downplaying his vaccine expertise, citing a variety of positions with pharmaceutical companies related to vaccines and a role as “NIH/NIAID Study Section Chair and Reviewer, Vaccine and Biodefense Programs (2010-2019)”. He does not link to his CV, and I cannot verify this, but even if Dr. Malone had more experience than the court pointed out, it does not change the qualifications of most committee members. 

The judge convincingly concludes that “A committee of non-experts cannot be said to embody ‘fairly balanced . . . points of view’ within the relevant scientific community. See 5 U.S.C. § 1004(b)(2). It is more accurate to say that they do not represent points of view within the relevant expert community.

Further, the membership does not comply with the CDC’s own ACIP “balance membership plan” in terms of the expertise members should have. 

The process to appoint these non-expert members was also flawed, ignoring prior practices – it was shorter, had no general notice in the federal register, and appeared to lack the careful examination that prior appointments to ACIP went through.

The court concluded that “little, if any, attention was paid by Secretary Kennedy to the requirements of FACA when appointing the new ACIP members,” and “Plaintiffs are likely to succeed in demonstrating that the reconstitution of ACIP was arbitrary and capricious.” The government never explained why it is ignoring the requirements in ACIP’s charter and the CDC’s internal documents. 

The January 2026 memo

The court found this memo “arbitrary and capricious” because of the lack of review by ACIP. The Administrative Procedures Act tells courts, among other things, to “hold unlawful and set aside agency action, findings, and conclusions found to be”… “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law;” (§706(2)(A)). In practice, this requires agencies to explain their decision well. I summarize this, citing the famous case of Motor Vehicle Association v. State Farm (1983) is a quote of two paragraphs of the case set out in an accessible way:  

Under the Arbitrary and Capricious Standard, 

Agencies Must:	[action is] invalid if the agency:
°Examine relevant data. °Give satisfactory explanation for an action. °Provide a rational connection between facts found and choice made.  °Consider relevant factors  (all). °Not rely on factors not included by Congress.	°Relied on factors Congress did not intend. °Ignored an important aspect of the problem.  °Offered an explanation that contradicts the evidence before the agency.  °Offered an implausible explanation.

Here, the judge found the memo arbitrary and capricious because HHS “abandoned the agency’s longstanding practice of getting recommendations from ACIP before changing the immunization schedules without sufficient explanation.” As the judge pointed out, just the president’s preference is not enough of an argument for a change. The agency actually needs to explain its actions on the substance. 

Frankly, I think the judge could have taken this memo apart much more deeply, since it simply did not explain a number of things. It did not explain the choice of peer countries, why follow Denmark rather than others.

It did not address the risks of removing routine recommendations for the vaccines, such as the potential for more disease cases. It did not address the fact that the memo only focused on a small selection of the scientific literature related to each vaccine it removed. But on what it did address, it made a very strong case that the memo was arbitrary and capricious, and the plaintiffs are likely to win their challenge against it. 

The May 2025 decision

On this, the judge found that this is not really before the court, and the plaintiffs are unlikely to win this challenge. That’s because either the decision was not in force until the CDC acted on it, and the CDC’s action was not completely in line with the short video by the Secretary, or it was mooted by later actions by ACIP and HHS. So the court did not stay that – but its other actions essentially put on hold the administration’s decisions about COVID-19 vaccines. 

Other factors

The court explained that plaintiffs showed irreparable harm – mostly financial costs they will never be able to recover, since no tort claim covers them if the memo is not stayed, and harms from additional actions of ACIP that will create more vaccine uncertainty. In terms of the balance of equities, the court said:

Plaintiffs and amici have demonstrated that there is a substantial risk to public health absent preliminary relief. See, e.g., Dkt. 218 at 26–35; Dkt. 228 at 24–30; Dkt. 237 at 55–58, 60–61. The Court finds it telling that Defendants make little effort to directly oppose this point, arguing only that Plaintiffs’ requested relief goes against the public interest by restraining Defendants’ speech. …. But as discussed above, the Court is not dictating what vaccine-related content Defendants may or may not espouse.76 Instead, the Court is regulating the procedure by which Defendants do so. “There is generally no public interest in the perpetuation of unlawful agency action.” Newby, 838 F.3d at 12. Thus, the Government “cannot suffer harm from an injunction that merely ends an unlawful practice.”

The remedy for AAP v Kennedy

The court concluded that it’s appropriate to stay the January 2026 memo, so it put it on hold. In relation to ACIP, the court concluded that the problems it identified cover the “appointment process, in general, and thus the full committee was tainted. Thus, the remedy should cover the entire challenged committee.” It refused to directly “enjoin”, or stop, ACIP from meeting, or to identify who should be on ACIP. Instead, it decided to “stay the appointments of the thirteen members of ACIP at issue in this motion.” What does this mean?

1. The previous members are not reinstated.
2. The appointment of the thirteen members whose appointment was before the court, not including the two newest ones, is stayed. That means their appointments are on hold until the end of the litigation: they cannot act as members of ACIP.
3. Secretary Kennedy, if he loses the full case, can still appoint ACIP members, but would have to consider the balanced membership requirements.
4. There is no decision about the two other members.

What about the meeting? “…while the appointments of the challenged members of ACIP are stayed, ACIP as currently constituted cannot meet, for how can a committee meet without nearly the entirety of its membership?” So until something changes, ACIP meetings are on hold.

To be clear: if the members in question want to meet and have discussions, make videos about any issue, and so forth, they are free to do so, but they are not meeting as ACIP and cannot make decisions as ACIP. 

Finally, the court put on hold prior ACIP’s votes – “ the Court will also stay all votes taken by the challenged ACIP, as they were taken by a committee that this Court has determined likely violates FACA.”

I have some questions here – for example, the new ACIP voted for Vaccines for Children Program coverage for the RSV vaccine. What happens to that vote? But on the plus side, some of the committee’s prior problematic votes – like the vote against protecting newborns from Hepatitis B – are on hold now. 

Note: contrary to some presentations, this decision does not undermine informed consent. As a reminder, informed consent is a requirement for vaccines regardless of whether they are recommended routinely or under shared clinical decision making. It does not address parental choice. It can help with access, though. 

What’s next for AAP v Kennedy?

That depends on what the government will do. Most likely, the government will appeal the decision. It is unlikely to be able to appeal to the Supreme Court, but it can try an appeal to the First Circuit. It is always tricky to assess the chance of an appeal like that, but if I had to bet, I would say that if the plaintiffs have anything to worry about, it is the standing issue – higher courts may be less generous in finding standing.

I think the government’s arguments on the merits are weak because the decisions have been very poorly explained. Whatever the First Circuit decides can, then, be appealed to the Supreme Court, which will have discretion whether to take the case, and discretion whether to put the lower courts’ decisions on hold. 

In the meantime, ACIP will not meet on March 18-19, and the CDC should revise the vaccine schedules to reflect the previous schedules. 

CDC Director and Secretary Kennedy still have the authority to change recommendations. But under this decision, they would have to – 

A. Explain why they are bypassing ACIP to issue recommendations, or doing so will still be deemed arbitrary and capricious.

B. Explain any recommendations well enough to withstand arbitrary and capricious review.

It’s possible that they can explain bypassing ACIP with the argument that ACIP membership is currently on hold because of the decision. But if they have not moved to create a valid ACIP, that explanation may not be good enough, unless it is a decision that really cannot wait

If the government does not appeal, or the appeal is denied, the case will proceed to full fact-finding and decision, and that, whatever it is, can also be appealed later.

Can a stay be appealed?

I have been getting a lot of questions about whether the fact that the judge issued a stay rather than an injunction means that you cannot appeal. After looking into it and discussing the question with experts, here is where I fall:

1. As a practical matter, the government can almost certainly appeal the stay, and the higher courts will likely consider that appeal on the merits, not dismiss it out of hand because it’s appealing a stay. There are legal arguments against this, and the AAP lawyers, as zealous advocates for their client, likely will raise them, but on this, I think they’re not likely to win. Just to reiterate, they do have an argument. 
2. This is highly confusing, and there are good reasons everyone is uncertain – the terminology has been changing, used imprecisely, and there is little recent direct discussion of this in cases. 

Below, I will elaborate on 1and 2 and then explain another reason for using a stay rather than an injunction here.

To get to this, I did my own case examination, read over any reference to section 705 of the Administrative Procedures Act in my Administrative Law textbook, talked to two civil procedures professors and one administrative law professor, and consulted with three experienced lawyers who routinely litigate against the government, including Attorney Joel Hoffman, who was involved in the Mifepristone cases.

1. There are different kinds of stays. A stay of a decision in a regular civil procedure is not appealable. But this is a stay under section 705 of the Administrative Procedures Act, which allows “relief pending review” – a stay of agency action – by the agency or by a court. Section 705 has been interpreted to allow either a stay or a preliminary injunction. Both are given under the same four conditions used to assess whether a preliminary injunction is appropriate. 
   
   Historically, it seems that it stays under s. 705 were not appealable. But in the recent Mifepristone decision, FDA v. Alliance for Hippocratic Medicine (which started with the parties reversed), the district court judge granted an administrative stay under §705, and in the appeal and in the Supreme Court, that was not a barrier. So my reading is that this is not a barrier to appeal.
   
   The Supreme Court appeared to have addressed this by saying that the district court “effectively enjoined” the result. So AAP’s wonderful lawyers can argue that that is not true here. But I suspect the higher courts will treat this as also “effectively enjoining” the decision. 
2. On the confusion, I will point to the fact that none of the experts I consulted had a good answer. Joel Hoffman summarized the confusion in what I think is the best way:

The terminology is very confusing, and getting more so by the day. In FDA v. AHM (mifepristone), according the Court (slip op. pp. 4-5), the District Court had “stayed” the effectiveness of the approval, but the Sup Ct said the district court had “effectively enjoined” FDA’s approval of the drug. The 5^th Cir then “stayed” the DCt’s order (in part). The SupCt then “stayed” the District Court’s order in its entirety. On remand, the 5^th Cir “vacate[d] the district court’s stay in its entirety.

Back in the day (my day), plaintiffs in APA cases asked for preliminary injunctions pendente lite and then permanent injunctions. The current fashion is to ask for “vacatur.” What used to be called a “stay” was not appealable, any more so than in other civil litigation. (But of course, the Court of Appeals could be asked to grant a “stay” if the District Court hadn’t done so, or to “vacate” a District Court “stay.”) So today you can get from the Supreme Court a stay of a stay of a stay.

None of this is made any clearer by the recently-invented “administrative stay” of a District Court order granting either a p/i or a “stay,” which either a Court of Appeals or the Supreme Court may grant while it considers whether to grant a [non-administrative?] stay of either a p/i or a “stay.” Whatever the original intent of its creator, some “administrative stays” have been allowed to remain in place for a pretty long time. There was a recent case in which the Supreme Court chastised the 9^th Cir (I think it was) for allowing an administrative stay to remain in force for several months without ruling on the underlying motion for a real “stay.”

Another Reason the Judge may have used a Stay:

Judge Murphy has had previous national injunctions overturned by the Supreme Court, so may hope that using a §705 stay may avoid those specific rulings. 

Conclusion

This is an important step for the plaintiffs, though it’s not the end of the case. At least for now, ACIP cannot meet, and the CDC should revise the vaccine schedule to reflect the current situation, as before Kennedy’s changes. The government will likely appeal, and this is, at any rate, a temporary remedy until the litigation is over. 

But it indicates that at least one court found the actions the Kennedy HHS took to be problematic and illegal, and it is a setback to the Secretary’s efforts to reduce vaccines available to children and to some of his actions in his battle to decrease vaccine rates.