To Spread Mistrust, Dr. Martin Kulldorff Asks RFK Jr. to do an Unethical, Impossible RCT of Vaccines He Knows Are Safe & Effective

In a plot twist nobody asked for, a biostatistician who literally helped design vaccine safety systems is now cheering on a fantasy trial that would leave kids unprotected from measles, polio, and other vaccine-preventable diseases. Dr. Martin Kulldorff has publicly urged Health and Human Services Secretary Robert F. Kennedy Jr. (RFK Jr.) to champion a massive randomized controlled trial (RCT) of the childhood vaccine schedulea trial he knows cannot be done ethically, legally, or practically. The proposal isn’t about learning anything new. It’s about creating the illusion that we haven’t already answered basic questions about vaccine safety and effectiveness, and using that illusion to sow more mistrust.

Let’s unpack what this RCT demand really means, why it directly contradicts decades of vaccine research ethics, and how it fits into a broader strategy to undermine confidence in one of the safest and most extensively studied interventions in medicine: routine childhood vaccination.

Who Are the Main Players in This Vaccine Drama?

Dr. Martin Kulldorff: From vaccine safety expert to political firebrand

Dr. Martin Kulldorff isn’t some fringe blogger shouting into the void. He’s a biostatistician and epidemiologist who has spent years working on systems used by the FDA and CDC to monitor vaccine safety in real time. For much of his career, he operated inside mainstream public health, developing methods to detect rare adverse events after vaccines are rolled out at scale.

More recently, though, he has become better known for co-authoring the Great Barrington Declaration and criticizing COVID-19 mitigation policies, aligning himself with an “anti-lockdown” movement and a political ecosystem that overlaps heavily with vaccine skepticism. In this newer role, he has increasingly framed mainstream public health as corrupt, opaque, and untrustworthyexactly the narrative that fuels vaccine hesitancy.

RFK Jr.: From environmental lawyer to HHS Secretary and vaccine skeptic-in-chief

Robert F. Kennedy Jr. started as an environmental attorney and activist. Over time, he became a central figure in the modern anti-vaccine movement, leading organizations that question vaccine safety, exaggerate risks, and downplay the benefits of immunization. That long history of vaccine misinformation now sits uneasily beside his current role as U.S. Secretary of Health and Human Services, where he oversees agencies like the CDC, FDA, and NIHthe very institutions that protect vaccine quality and safety.

Kulldorff’s call for RFK Jr. to oversee a huge RCT of the childhood vaccine schedule is framed as a way to “restore trust” in vaccines. In reality, it weaponizes mistrust: if the trial doesn’t happen (and it won’t), skeptics can accuse “the establishment” of hiding something. If it somehow did happen, it would expose children to preventable disease for the sake of optics.

What Exactly Is the “Impossible RCT” They Keep Talking About?

The randomized controlled trial being floated sounds, at first, like “gold standard science”: split children into groups, give some the routine childhood vaccine schedule on time, delay or omit vaccines in others, then compare long-term outcomes. This is the vision anti-vaccine activists have been selling for yearsa giant, placebo-controlled experiment on vaccinated versus unvaccinated kids.

Kulldorff’s twist is to suggest randomizing the age at which children receive vaccines, such as giving the measles-mumps-rubella (MMR) vaccine at one year versus three years of age, and spreading these children out geographically so clusters of unvaccinated kids don’t form. On paper, it sounds neat and tidy. In the real world, it would mean millions of kids walking around for years without protection from diseases that can hospitalize or kill them.

Even more troubling, Kulldorff knows this is unworkable. In a previous, more conventional phase of his career, he explicitly acknowledged in a National Academies report that randomized trials in which one arm is left unvaccinated, or significantly delayed, are unethical because they knowingly expose children and communities to vaccine-preventable diseases. He correctly noted that such designs would also erode herd immunity and harm children who never agreed to be part of the experiment. His current proposal contradicts his own written analysis.

Why the RCT Is Scientifically Unnecessary

We already have randomized trials and mountains of safety data

Demanding a brand-new mega-RCT of the entire childhood vaccine schedule pretends that vaccines somehow skipped rigorous testing the first time around. That’s simply false. Childhood vaccines go through the same multi-phase development process as other drugs: laboratory work, animal studies, and then carefully designed clinical trials in humans, often including placebo-controlled or active-comparator RCTs. Only after demonstrating safety and efficacy are vaccines licensed, recommended, and added to the immunization schedule.

Once approved, vaccines are continuously monitored through multiple, overlapping systems that track safety in real-world use, including large health database networks designed to pick up even very rare adverse events. These systems have operated for decades and involve millions of doses and millions of children. They are far more informative about real-world safety than a single, time-limited RCT could ever be.

In other words, the demand for “just one more giant RCT” ignores the enormous body of research already in place. It’s like insisting we need a randomized trial to check whether seat belts prevent injuries in car crashesit may sound “scientific,” but only if you ignore everything we already know.

Modern ethics don’t allow you to pretend we know nothing

In clinical research, the key concept is equipoisegenuine uncertainty about whether one intervention is better than another. You can ethically randomize people between treatments only when you honestly don’t know which option is superior. When vaccines have already been shown to prevent serious disease and death, and when withholding them exposes children to those risks, equipoise disappears. At that point, randomizing children to “no vaccine” or “much later vaccine” is not heroic science; it is knowingly increasing their risk of harm.

This is why ethical frameworks and regulatory rules worldwide are clear: once a vaccine is proven safe and effective, new vaccines are generally compared to the existing standard, not to a placebo that offers no protection. Demanding fresh placebo-controlled trials for long-established vaccines is not about better ethics or better science. It’s about creating a moving target so no amount of evidence is ever “enough.”

Why the Trial Is Deeply Unethical

Withholding vaccines means preventable harm

An RCT of the sort Kulldorff describes would create a large group of children who are intentionally left unprotected for years in order to see what happens. We are not talking about a theoretical risk. Measles, pertussis, polio, and other diseases still exist and can return quickly when vaccination rates drop. History has shown, repeatedly, that when pockets of under-vaccinated people form, outbreaks follow.

The harm wouldn’t be limited to the children whose vaccines were delayed or replaced with placebo. Because infectious diseases spread, babies too young to be fully vaccinated, immunocompromised people, and others who never consented to the trial would be placed at higher risk. That violates one of the most basic principles of research ethics: you don’t get to endanger non-consenting third parties as collateral damage in your experiment.

We’ve already seen what happens when we ignore ethics

The idea of withholding effective interventions “for the sake of science” has a dark history. Past abusesincluding notorious studies in which proven treatments were kept from participantsare precisely why we now have strict rules, independent ethics boards, and international guidelines. These frameworks exist so we don’t repeat tragedies under the banner of “research.”

A trial that deliberately withholds routine vaccines or significantly delays them would run directly into those guardrails. Institutional Review Boards are tasked with rejecting trials that expose participants to unnecessary, avoidable risk. A mega-RCT of the vaccine schedule would almost certainly be rejected on that basis alone. Kulldorff, who has worked closely with regulatory and monitoring systems, knows that. Which leads to the uncomfortable conclusion that his proposal is not meant to be implemented, only advertised.

Why the Trial Is Practically Impossible

Good luck recruiting parents for a 50/50 chance at no protection

Picture the informed consent conversation: “We’d like to enroll your child in a study where there’s a 50% chance they’ll get the usual vaccines on schedule, and a 50% chance they’ll receive nothing (or receive them years late). You won’t know which group they’re in, and during that time they could be exposed to measles, pertussis, or polio.”

How many parents would say yes to that? Anti-vaccine activists might imagine lines around the block. In reality, recruiting enough families who fully understand and accept that risk would be enormously difficult. The families most likely to agree would already be highly skeptical of vaccines, making the trial hopelessly biased from the start. Meanwhile, parents who do trust vaccines (i.e., the vast majority) would be understandably horrified by the idea.

Massive scale, chaotic variables, and moving targets

To detect differences in rare outcomeslike specific neurodevelopmental diagnoses or extremely uncommon side effectsyou’d need hundreds of thousands, if not millions, of children followed for years. Over that time, the world doesn’t stand still: new vaccines are introduced, pathogens evolve, healthcare systems change, and other exposures (pollution, diet, infections) shift. Trying to attribute small differences in outcomes between groups to the timing of vaccines in such a dynamic environment would be scientifically messy at best.

Meanwhile, existing observational studies, large health databases, and targeted mechanistic research already give us far cleaner signals about vaccine risks and benefits. The mega-RCT sounds impressive on talk shows, but as an actual study design, it’s an inefficient and ethically indefensible way to answer questions we’ve largely already answered.

How Demanding an “Impossible RCT” Spreads Mistrust

The rhetorical trick: “If vaccines are so safe, just prove it again”

On the surface, calls for more trials sound like reasonable caution. Who doesn’t want more data? But in the context of vaccines, demands for a massive new RCT of the entire schedule are a classic example of shifting the goalposts. When decades of research, multiple RCTs, and global surveillance all say vaccines are safe and effective, insisting that only one very specific, currently forbidden trial would be “good enough” is not curiosityit’s sabotage.

If public health officials refuse to launch such a trial (because it’s unethical), critics can claim they’re hiding something. If they somehow did launch it and it reaffirmed vaccine safety, opponents could simply move on to the next condition, the next subgroup, or the next hypothetical mechanism, insisting that “the right” trial still hasn’t been done. The bar keeps moving, and trust erodes further with every manufactured controversy.

Undermining institutions from the inside

When someone with Kulldorff’s background pretends that we haven’t tested vaccines properly, he sends a powerful signal to people who don’t follow the details: “See? Even the experts say the science isn’t settled.” When RFK Jr., now in charge of HHS, embraces rhetoric that questions long-standing vaccine policies, it amplifies the message that ordinary families should be suspicious of established medical guidance.

That’s the real purpose of the impossible RCT: not to learn something new, but to create a permanent storyline in which “the establishment” is always ducking the one trial that would supposedly settle everything. It is an elegant way to keep doubt alive forever.

What Does Real Science-Based Vaccine Research Look Like?

Real science-based medicine doesn’t treat children like chess pieces in a political game. Instead, it relies on layered, complementary methods:

• Pre-licensure RCTs to show that a vaccine works and meets safety standards before it’s approved.
• Post-marketing surveillance using large databases to detect rare side effects once millions of doses are given.
• Comparative effectiveness studies that examine different dosing schedules or formulations without withholding protection from any group.
• Ongoing safety monitoring systems that work together to flag unexpected patterns, investigate them, and revise recommendations if needed.

This is not a vacuum of research; it’s one of the most intensely scrutinized areas in all of medicine. Vaccines are given to healthy children, so regulators hold them to especially high standards. And when rare safety issues do emergesuch as very rare clotting events with certain vaccinessystems have repeatedly shown they can detect, investigate, and respond to those signals.

How to Talk About These “Unethical RCT” Demands With Patients and the Public

For clinicians, public health professionals, and science communicators, it’s not enough to say, “That trial would be unethical” and move on. People want to understand why. Here are some practical ways to frame the issue:

• Explain that randomized controlled trials are crucial before a vaccine is approvedbut once a vaccine clearly prevents serious disease, it’s unethical to randomize children to “no protection.”
• Compare it to other areas of medicine: we don’t randomize people to “no insulin” once insulin is known to save lives, just to double-check.
• Highlight the systems that monitor vaccine safety after approval and how they’ve successfully detected rare side effects in the past.
• Clarify that calls for a mega-RCT ignore decades of existing research and would not magically convert entrenched skeptics. The people loudly demanding these trials often dismiss the RCTs we already have.

Most parents are not ideologuesthey’re simply trying to make safe choices for their kids. When they see public disagreements between experts, they can understandably feel anxious. Walking them through how we actually evaluate vaccine safety, and why certain trials are off-limits, is far more reassuring than simply saying, “Trust us.”

Experiences and Real-World Lessons From the Rhetoric of “Impossible Trials”

Although a literal mega-RCT of the vaccine schedule has (thankfully) never been done, we’ve seen the effects of talking about such trials as if they are the only legitimate science.

In community forums and school board meetings, parents sometimes repeat talking points they’ve heard from high-profile skeptics: “Why won’t they just compare vaccinated and unvaccinated kids in a big trial? What are they afraid of?” For clinicians, this can feel like déjà vu. The same question appears again and again, framed as a common-sense request. Doctors report spending precious appointment time walking families through why you can’t ethically withhold vaccines just to satisfy political demands masquerading as scientific ones.

Public health departments have also learned that once the “impossible RCT” idea takes hold, it changes how people interpret all existing evidence. If you’ve been told that “real science” means one specific trial design that will never happen, then every other form of evidenceobservational studies, smaller RCTs, decades of post-marketing datacan be dismissed with a shrug. The bar for proof has been moved to a place no responsible scientist can reach.

On the ethics side, members of institutional review boards have described a new kind of pressure. They occasionally see proposals, or at least public suggestions, that flirt with designs which would leave some participants without known-effective care, justified by claims that “people are demanding answers.” IRB members are forced to be the adults in the room, reminding everyone that the purpose of research is to improve health, not to retroactively satisfy political narratives. Saying “no” to an unethical trial can be thankless work, but it is essential.

Science communicators and medical educators have adapted too. Many now proactively teach about research ethics, equipoise, and the history of past abuses to both students and the public. When audiences understand why certain lines cannot be crossed, they’re less swayed when someone insists that crossing those lines is the only way to regain trust. Instead of seeing ethical limits as “stonewalling,” they start to see them as guardrails that keep research humane.

Perhaps the most sobering experience comes from communities that have actually lived through outbreaks triggered by declining vaccination rates. When measles flares up in a region where vaccine uptake has dropped, there is nothing theoretical about the risks of delaying immunization. Parents of children in intensive care units do not ask why no one randomized their child into a placebo group; they ask why misinformation was allowed to spread unchecked for so long.

The lesson from all of this is simple but uncomfortable: demands for unethical, impossible RCTs are not innocent suggestions. They shape public expectations, distort what “real science” is supposed to look like, and make it easier for people to dismiss the robust evidence we already have. Recognizing that patternand calling it what it ismay be one of the most important things clinicians, scientists, and journalists can do in the current environment.

In the end, the most science-based response to calls for an impossible vaccine RCT is not to play along with the fantasy, but to explain clearly why good science and good ethics both lead us in the opposite direction. Protecting children from preventable disease is not a “parlor game” or a bargaining chip in a political feud. It’s the whole point.