Sen. Bernie Sanders Confronts RFK Jr. On Germ Theory Denial as Bill Cassidy Debunks Anti-Vaccine Claims in Senate Hearing

In a Congressional hearing on Wednesday, Sen. Bernie Sanders (I-Vt.) directly confronted Health Secretary Robert F. Kennedy Jr. On his rejection of germ theory—the scientific principle that specific pathogenic microbes cause specific diseases. Kennedy defended his fringe view, while Senator Bill Cassidy fact-checked and debunked Kennedy’s denialist arguments in real time.

The exchange marked a rare instance in which Kennedy’s dismissal of germ theory was raised in such a high-profile public setting, occurring during a hearing of the Senate Committee on Health, Education, Labor, and Pensions. Kennedy, who has no background in science, medicine, or public health, is well known as an ardent anti-vaccine activist and promoter of conspiracy theories. However, his rejection of germ theory—a cornerstone of biomedical science—has largely gone underreported.

As Ars Technica reported last year, Kennedy wrote explicitly about his germ theory denialism in his 2021 book The Real Anthony Fauci. In it, he characterizes germ theory as a tool used by pharmaceutical companies, scientists, and doctors to promote modern medicines. Instead, Kennedy advocates a concept similar to the discarded terrain theory, which claims diseases arise from imbalances in the body’s inner “terrain” due to poor nutrition and exposure to environmental toxins and stressors.

Kennedy erroneously labels this concept as “miasma theory” in his book, but miasma theory is distinct—it attributes disease to breathing bad air, vapors, or mists from decaying matter. While germ theory replaced miasma theory, terrain theory was never widely accepted in the scientific community.

During the hearing, Kennedy faced direct questioning about his views. Sanders pressed him on the scientific consensus behind germ theory, while Cassidy provided real-time corrections to Kennedy’s claims, highlighting the lack of evidence supporting his alternative explanations for disease causation.

The hearing underscored ongoing concerns about Kennedy’s influence on public health policy, particularly given his role as Secretary of Health and Human Services. His views have drawn criticism from public health experts and lawmakers across the political spectrum for contradicting established medical science.