RFK Jr. is a famous anti-vaxxer. How does this make him qualified for President?

I’ve written about the anti-vaccine movement and its many proponents more times than I can count. So why write about it again? Because one of them is running for President of the United States.

Robert Kennedy Jr. is famous for two things: first, he’s famous because he’s the son of a former Senator and the nephew of a former president. His father, Robert Kennedy Sr., served as Attorney General under President John Kennedy and then as a US Senator. Tragically, both JFK and RFK were assassinated in the 1960s, and RFK might very well have been elected president in 1968, as he was leading the Democratic field when he was killed.

Having a politician as one’s father does not qualify anyone for office, although many children of politicians use their famous name to win elections. That’s clearly what RFK Jr. is now hoping for.

But what RFK Jr. is really famous for now, and for the past 20 years, is something entirely different. As I wrote nearly a decade ago, Kennedy is obsessed with the notion that vaccines cause autism. He’s particularly obsessed with the thoroughly discredited idea that thimerosal, a preservative used in some vaccines, causes autism.

His efforts to convince people of the harms of vaccines landed Kennedy in the number two position on the infamous list of “The Disinformation Dozen,” This list, created by the Center for Countering Digital Hate, contains “the twelve anti-vaxxers who are responsible for almost two-thirds of anti‑vaccine content circulating on social media platforms.” Yes, this is what RFK Jr. has been focusing his energy on, at least until he decided to run for President.

Ten years ago, Kennedy published an entire book on this topic, called “Thimerosal: Let the Science Speak,” and he promoted it both in the press and in the halls of Congress. He had personal meetings with then-U.S. Senator Barbara Mikulski and Sen. Bernie Sanders to try to convince them to take action based on his claims. Why is it that a scientifically unqualified anti-vaccine advocate got a private audience with two U.S. Senators? Because he’s a Kennedy.

RFK Jr. gives hundreds of speeches a year, and up until the early 2000s, he spoke mostly on environmental issues. I heard one or two of his interviews during that era, and he was quite convincing. His usual argument was that large corporations were engaged in some kind of conspiracy to damage the environment so that they could increase their profits. That made sense to me!

But then he found the thimerosal issue and went completely off the rails. One example was a Salon.com and Rolling Stone article (jointly published in both magazines) that he wrote in 2005, which claimed not only that thimerosal-containing vaccines cause autism, but that “the government” knew about it and had been covering it up. Kennedy wrote that

“The story of how government health agencies colluded with Big Pharma to hide the risks of thimerosal from the public is a chilling case study of institutional arrogance, power and greed.” [quote from RFK Jr.]

Alarming-sounding stuff. The article was full of dramatic claims like this one. The only problem was, all of them were false.

To explain, let’s review what thimerosal is and why it has probably saved many lives. There was never a conspiracy because there was nothing to hide.

Thimerosal is a preservative that was used in many vaccines for decades. Why? Well, as I’ve explained before, early vaccines (back in the pre-WWII era) were administered from multi-dose bottles, in which bacteria would sometimes grow. In one particularly disastrous incident in 1928, 12 children in Australia died from staph infections after receiving the diptheria vaccine from the same multi-dose bottle. After the introduction of thimerosal, bacterial infections caused by vaccination virtually disappeared.

Why the panic from RFK Jr. and others about thimerosal? Well, it’s a mercury-based preservative, and RFK assumed (wrongly) that the tiny amounts of ethylmercury in vaccines caused autism or other neurological problems. One problem with this idea is that ethylmercury is very different from environmental mercury, which is called methylmercury and which can indeed be toxic. Ethylmercury is cleared from the body far more quickly–and the minuscule amounts in vaccines have never been shown to cause any harm.

But many anti-vaxxers, especially RFK Jr., have continued to spread alarming stories about vaccines (particularly through Children’s Health Defense, an organization founded by Kennedy), and a disturbing number of parents have withheld vaccines from their children because they didn’t know who to believe.

In the late 2000's, in an effort to address the concerns of anti-vaccine alarmists, a special U.S. vaccine court conducted three lengthy hearings in which the anti-vax advocates were asked to present their best cases. One of the cases focused specifically on the question: does thimerosal in vaccines cause autism? In that case, the judge concluded:

“The numerous medical studies concerning the issue of whether thimerosal causes autism, performed by medical scientists worldwide, have come down strongly against the petitioners’ contentions. Considering all of the evidence, I find that the petitioners have failed to demonstrate that thimerosal-containing vaccines can contribute to the causation of autism.”

As a lawyer, Kennedy should have been able to understand this. The science agrees with the court: in study after study, scientists found no link between thimerosal and autism or any other kind of neurological disorder. That should have been the end of the matter, but of course it wasn’t.

Furthermore, as RFK Jr knows, thimerosal was removed from childhood vaccines in the U.S. over 20 years ago, and the rate of autism diagnosis continued to rise after that. This fact alone contradicts his major claim: if thimerosal was fueling an autism epidemic, then cases should have declined after vaccines stopped including it.

What was shocking to me, the first time I heard Kennedy talk about thimerosal in vaccines, was how absolutely certain he was. He came across as a man who remained utterly convinced that vaccines cause autism, despite the mountain of evidence against him.

After RFK Jr.'s Salon article appeared, scientists responded quickly and convincingly, pointing out its numerous flaws and distortions. Salon tried to fix the problem, issuing five corrections before throwing up their hands and removing the article entirely from their website. Rolling Stone also took down the article. Salon’s editor-in-chief wrote an apology, saying

“I regret we didn’t move on this more quickly, as evidence continued to emerge debunking the vaccines and autism link. But continued revelations of the flaws and even fraud tainting the science behind the connection make taking down the story the right thing to do .”

Kennedy has steadfastly refused to admit any errors, ever. When I wrote about him in the past, his website still displayed the original Salon article, without even the small corrections that Salon.com had made. (That website, robertfkennedyjr.com, no longer exists now that he’s running for President.)

Kennedy also published another anti-vaccine book just last year, titled “Vax-Unvax: Let the Science Speak.” (In case you didn’t notice, Kennedy has zero credentials to write a book about vaccine science, but that has never slowed him down.) And in case there’s any doubt about his leanings, early in 2024 Kennedy hired Del Bigtree, a “top anti-vaccine activist,” as his campaign communications director.

By ignoring the scientific evidence that shows that thimerosal and vaccines have no link to autism, Robert Kennedy placed himself firmly in the camp of conspiracy theorists and cranks. He’s also demonstrated breathtaking arrogance. He believes that despite his lack of scientific training, he knows the truth that every scientist who’s studied this issue has missed.

Even worse, Kennedy has used his fame to spread anti-vaccine misinformation, which grew far worse during COVID. Though I doubt he will listen to me (he’s ignored everyone else), Kennedy needs to take a hard look at the harm he’s causing to defenseless children, the elderly, and cancer patients, and anyone else with a weak or compromised immune system.

When I heard Kennedy talk about environmental topics, where I agreed with him, I was impressed by his passion and his seeming command of the issues. But having heard him speak about thimerosal and vaccines, I now realize that he’s a dangerous ideologue, willing to distort the truth so thoroughly that he can’t be trusted on any topic, even ones where I agree with him. His campaign for President, although certainly doomed to fail, is likely to increase the spread of his harmful anti-vaccine tropes.

Finally, I couldn’t help but notice that the bio on RFK Jr’s campaign’s website makes no mention of his anti-vaccine activism, even though it’s been his top priority for the past 20 years, and it’s the main reason he has the visibility he has today. It does mention “his nonprofit, Children’s Health Defense” but doesn’t say that the primary work of that nonprofit is to spread scary misinformation about vaccines. I’m just guessing here, but it appears that some of his campaign advisers have decided that being a famous anti-vaxxer might not be the best qualification for President.

Update, May 28, 2024: Since this story was published on May 27, RFK Jr. has been contacted for comment.  

Hormone replacement therapy is beneficial and safe, it turns out


A new study that just appeared in the Journal of the American Medical Association has some good news for women who take estrogen replacement therapy.

To jump to the punch line: estrogen therapy helps to alleviate hot flashes and other symptoms of menopause, and it carries little risk. And even better news: the study also reported that estrogen-only therapy might actually decrease the risk of breast cancer.

Why does this matter? Because about 20 years ago, millions of women stopped taking estrogen, even if it was helping them, because of a report that hormone replacement therapy might increase (not decrease) the risk of breast cancer.

These latest results come from the long-running Women’s Health Initiative, a National Institutes of Health-funded study of more than 160,000 women who were given various hormone therapies and then followed for up to 20 years. The WHI was responsible, somewhat notoriously, for the cancer scare in 2002, when the NIH reported–without consulting many of the scientists leading the study–that hormone replacement therapy increased the risk of breast cancer. This was wrong, as I explained in this column a few years ago, but as a result, many women stopped taking estrogen, and physicians stopped recommending it.

The confusion stemmed from the use of two different types of hormone therapy: (1) estrogen alone, or (2) estrogen plus progestin. The increased risk occurred solely in the combination therapy group (estrogen plus progestin), and not in the estrogen-only group. Despite this crucial difference, the WHI halted the studies of both treatments in 2002, and their press releases didn’t fully explain the difference.

And yet, as Dr. Robert Langer explained in 2017, the WHI trial of estrogen alone (without progestin) continued to track its subjects, and in 2004 that study reported that estrogen-only therapy led to a reduction in breast cancer, and a reduction in coronary heart disease as well.

(Aside: the Women’s Health Initiative website boasts that their 2002 report contains “revolutionary findings about combined hormone therapy,” emphasizing only the harm. I couldn’t find any comparable highlight describing the benefits of estrogen-only therapy.)

The new study, which appeared in JAMA on May 1, confirms several earlier studies that have reported a cancer benefit for estrogen therapy. In addition to its beneficial effects on menopause symptoms (which are widely acknowledged), the new study found that, after an average of 10.7 years, “rates of breast cancer were significantly lower in the CEE group [estrogen only] compared with the placebo group (HR, 0.77).” That HR value means that women who took estrogen had a 23% reduction in their risk of breast cancer.

Further supporting these findings is a 2022 study from NIH, available as a preprint in medRxiv here, which found that women taking estrogen only, compared to no hormones at all, had “significant risk reductions for all study cancers, breast, lung, endometrial, colorectal and ovarian” as well as a 20% reduction in mortality. The 2022 NIH study also found, similarly to the 2002 findings from WHI, that when estrogen was combined with progestin, the risk of breast cancer increased.

And there’s more. This 2012 study out of Denmark studied women who received estrogen-only therapy for 10 years starting in the early 1990s. They then followed these women for another 16 years, and found that women taking estrogen had a lower risk of heart attack, heart failure, or death–and no increased risk of cancer.

(As another aside: the new JAMA paper also reported results on a completely separate study of calcium plus vitamin D. They found that taking supplemental calcium+D didn’t provide any benefit in reducing the risk of bone fractures, confirming what I wrote in a recent column, here.)

So what’s the bottom line? We now have a raft of evidence showing that for post-menopausal women, estrogen therapy can offer significant benefits not only in treating hot flashes and other “bothersome menopausal symptoms” (to quote JAMA), but also in reducing the risk of some types of cancer. In contrast, hormone replacement therapies that use progestin, which is commonly used in birth control pills, might increase the risk of cancer and should be avoided.

As with most medical treatments, the true picture is complicated, but millions of women today might benefit from estrogen therapy. If you think you might be one of them, talk to your physician.