Since assuming the role of secretary at the health and human services department (HHS), Robert F Kennedy Jr. has persistently cast doubt on vaccines. He has dismissed the entire panel advising the Centers for Disease Control and Prevention (CDC) on vaccines, restricted the availability of critical Covid-19 vaccines, appointed conspiracy theorists to scientific advisory boards, and terminated the new CDC director for declining to endorse his decisions without question.

However, his stance on vaccines is just a fraction of the issue. Secretary Kennedy is unsuitable as the nation’s foremost public health leader because he denies the core fundamentals of contemporary science.

For generations, doctors have agreed that germs – like bacteria or viruses – cause infectious diseases.

During the 1850s, John Snow, recognized as the progenitor of epidemiology, identified a cholera outbreak source in London as water tainted with human waste, contradicting the prevailing belief at the time that “bad air,” or miasma, was responsible.

In the 1880s, the French chemist Louis Pasteur demonstrated through a controlled experiment that vaccinating sheep with an anthrax vaccine helped them survive after being exposed to anthrax bacteria, unlike those that were not vaccinated.

The germ theory led to a revolution in public health and medicine which, over the years, has saved tens of millions of lives.

Just a few examples.

At a time when many women were dying during childbirth at hospitals, Dr Ignaz Semmelweis found that handwashing by doctors saved lives.

Joseph Lister showed that sterilizing medical equipment before surgery prevented needless deaths.

Florence Nightingale, hailed as the pioneer of modern nursing, significantly enhanced hospital hygiene, making healthcare far safer for patients.

Pasteur made the food we eat and the milk we drink safer through a process of heating called pasteurization.

And these are just a few examples.

Astonishingly, in 2025, we witness an HHS secretary who is skeptical of the germ theory— the cornerstone of modern medicine for more than a hundred years.

In his book The Real Anthony Fauci, Kennedy absurdly claims that the central tenet behind the germ theory “is simply untrue”. Vaccines are not, Kennedy falsely asserts, responsible for the massive decline in deaths from infectious diseases. Instead, Kennedy falsely proclaims that “science actually gives the honor of having vanquished disease mortalities to sanitation and nutrition”.

Yes. No one disputes that proper sanitation, a nutritious diet and exercise can lead to healthier lives. But no credible scientist or doctor believes that alone makes a person immune from polio, measles, mumps, Covid, HIV/Aids and other infectious diseases. Otherwise healthy people can become sick, hospitalized or even die from these and other terrible diseases.

Sadly, Kennedy’s dangerous rejection of well-established science is behind his wild conspiracy theories and misinformation campaigns.

It’s what led to Kennedy’s false assertion that “there is no vaccine that is safe and effective” despite peer-reviewed scientific studies finding that vaccines have saved more than 150 million lives and reduced infant deaths by 40% in the past 50 years.

It’s behind Kennedy’s bogus claim that the polio vaccine “killed many, many, many, many, many more people than polio ever did”, even though the scientific data has shown that the polio vaccine has saved 1.5 million lives and prevented about 20 million people from becoming paralyzed since 1988.

It undergirds his history of promoting the ridiculous idea that HIV does not cause Aids, despite rigorous studies finding the exact opposite. This type of outrageous HIV/Aids denialism is widely believed to have caused the deaths of at least 330,000 people in South Africa who did not receive the life-saving medicine they needed.

It’s what led him to say that the Covid vaccine was the “deadliest vaccine ever made”, that vaccines cause autism, and that the hepatitis B vaccine doesn’t work and should only be used for “prostitutes” and “promiscuous gay men” – lies that have been thoroughly debunked by scientific data and the medical community.

Frighteningly, it’s what caused Kennedy to say: “I see somebody on a hiking trail carrying a little baby and I say to him, ‘Better not get him vaccinated.’ And he heard that from me. If he hears it from 10 other people, maybe he won’t do it.”

As a private citizen, Kennedy is entitled to his views, no matter how misguided they may be.

If Kennedy would like to swim in water contaminated by raw sewage and fecal matter, as he has done recently in Washington DC’s Rock Creek Park, he is free to do that.

But as our nation’s top health official, Secretary Kennedy’s rejection of science and the actions he has taken as a result of his bizarre ideology is endangering the lives of millions of children in the United States and throughout the world.

Today, Kennedy is making it harder for people to get vaccines. Tomorrow, what will it be? Will he tell doctors they don’t need to wash their hands before surgery? Will he tell hospitals that they don’t need to sterilize their scalpels and other medical equipment?

The American people need a secretary of HHS who will listen to scientists and doctors, and not conspiracy theorists.

We need a secretary of HHS who will listen to medical experts who may disagree with him, not fire them summarily.

Bottom line: we need an HHS secretary who will not engage in a war on science and the truth itself.

Secretary Kennedy must step down.

• Bernie Sanders is a US senator, and ranking member of the health, education, labor and pensions committee. He represents the state of Vermont and is the longest-serving independent in the history of Congress