Secretary of Health and Human Services, Robert F. Kennedy Jr., wants Americans to believe that vaccine science is broken. His latest crusade is a demand for more “placebo-controlled trials,” as if vaccine makers have been hiding something by not giving some people sugar water instead of vaccines that have proven to work. It invokes the language of scientific rigor, while ignoring both medical ethics and its fraught history.

What are the ethical concerns for placebo-controlled vaccine trials?

At first glance, a placebo-controlled trial might sound like the gold standard. But in reality, placebo-controlled vaccine trials are often unethical, especially for new versions of existing vaccines—and for good reason. Once a vaccine has been proven to work, it’s no longer acceptable to deny people access to it in the name of experimentation.

The idea of denying people proven medicines in the name of research has a dark legacy in this country, most infamously the Tuskegee syphilis study. For four decades, Black men were denied penicillin—not for lack of evidence, but so government researchers could observe the effects of untreated disease. That study was not just unethical, it was lethal.

Now, imagine testing a new measles vaccine by giving half the children a placebo—even though we already have a safe, effective shot that could prevent a deadly illness. Again, that’s not good science. It’s a violation of basic medical ethics and will be lethal, too.

In his Make America Healthy Again (MAHA) report, Kennedy implies support for placebo-controlled trials that would withhold standard childhood vaccines—a move that, if implemented, would violate the same research ethics established in the wake of Tuskegee. The report fails to grapple with a simple truth: once a vaccine is proven safe and effective, testing new versions against a placebo is not just unnecessary. It’s unethical.

That principle is enshrined in U.S. regulations. The Common Rule, the backbone of U.S. protections for human research subjects, requires that researchers use no more than “minimal risk” and avoid exposing participants to unnecessary harm. A placebo-controlled trial that withholds a proven vaccine clearly violates this standard and exposes participants to infectious diseases.

The FDA has its own layer of protection through regulations governing how experimental drugs and vaccines are tested in humans. Before any trial can start, researchers must submit an Investigational New Drug (IND) application. This includes detailed plans for how the trial will be run, including a description of how measures will be taken to minimize risk to participants. An Institutional Review Board (IRB) signoff is needed to protect rights and welfare of human subjects.

To be clear, placebo-controlled trials can be ethical, even essential, when no vaccine or standard of care exists. For example, testing a vaccine for a novel virus or using a completely new antigen may justify a placebo arm. But that’s not what Secretary Kennedy is advocating. He’s calling for placebo trials even when effective vaccines already exist, where the risk is no longer theoretical, but real and avoidable.

And this ethical standard isn’t unique to vaccines. In drug trials for conditions like hypertension or chronic pain, researchers don’t test new treatments against placebos when proven therapies already exist, they compare them to the standard of care. Withholding blood pressure medications or pain medications in a clinical trial when effective therapies already exist would be widely recognized as unethical, exposing participants to preventable harm solely for the sake of generating additional scientific data.

In a functioning system, the kind of placebo-controlled vaccine trials that Secretary Kennedy is calling for would never get past an IRB, much less progress to an IND application. Vaccines are being singled out and politicized in a way that would never be tolerated for other medical products.

But with Trump back in office, Kennedy at the helm of HHS, and Dr. Marty Makary—another vaccine skeptic—leading the FDA, these agencies, once global leaders in biomedical ethics, are now being used to undermine public confidence and re-litigate settled science and being reshaped from the top down.

This is clear in a recent article co-authored by FDA Commissioner Marty Makary and Center for Biologics Evaluation and Research Director Vinay Prasad published by the New England Journal of Medicine, which acknowledges that placebo-controlled trials might be appropriate in low-risk populations—and only where genuine scientific uncertainty exists and no proven intervention is available. Yet even this proposal, cautious as it sounds, opens the door to ethically fraught studies. The article calls for post-marketing trials of COVID-19 vaccines in healthy adults that could include placebo arms, despite bioethics guidance warning against such designs when effective options already exist. It’s a troubling shift in tone from the agency that once set the global standard for research ethics.

This is no longer a theoretical concern. It’s happening.

Among the required post-marketing studies listed in FDA’s May 2025 approval letter for Novavax’s COVID-19 vaccine is a Phase 4 placebo-controlled trial in adults aged 50–64 without high-risk conditions. In other words, this administration is already mandating placebo use in a population where safe, effective vaccines exist—effectively testing whether doing nothing is better than continuing established immunization.

This, coupled with the rhetoric in the MAHA report, means that we will soon see unethical trials that expose children and other vulnerable populations to preventable illness in the name of “further testing.” Placebos will be given where real vaccines should be. Proven public health measures will be sidelined as misinformation gets rebranded as scientific dissent. And when harm inevitably occurs, the new leadership may call it a price worth paying for “transparency.”

In addition to being ethically fraught, call for placebo-controlled trials is a blow to vaccine innovation. Under the Common Rule, participants must give informed consent, meaning they must fully understand that receiving a placebo instead of a proven vaccine carries the real risk of serious, preventable illness. Once those risks are clearly explained, how many people would actually enroll? How many parents would agree to subject their children to these trials? The answer is likely very few. And that’s the point. The result will be a chilling effect on vaccine innovation.

Make no mistake: when we repeat that mistake by withholding proven vaccines under the guise of gold standard science, people—specifically, children—will die.