A Scientific Review of Claims made by RFK Jr.

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William FanRC YuJonathan KatzLee Johnson
Lee Johnson6 days ago
measles

Claim: Two Recent “Measles-Associated” Deaths May Have Been “Fabricated”

Verdict: Broadly false, but some questions remain open

“The announcement appears to have been premature, and the deaths may even have been altogether fabricated by one of the Governor's hopeful staffers. The Lancaster County Coroner says that it has no record of any measles deaths. State law requires that all measles deaths be reported to the coroner.” – RFK Jr

Governor Shapiro's unseemly rush to Lancaster County to convene a national press conference and his…

Two deaths that the Pennsylvania Department of Health called “measles-associated” have been at the centre of a political firestorm this week. RFK Jr. said these deaths may have been “fabricated,” but more broadly, disputes that measles was the cause of death.

The Two Deaths: What We Know

A great FactCheck.org post runs through the details of the deaths. In short, while few details have been released, we do know that two individuals died, that they had not been vaccinated and that they had confirmed measles infections. While we know next-to-nothing about one case, the other case has since been confirmed to have been an infant whose primary cause of death was a “traumatic laceration of the spleen.”

This child contracted measles before birth and died shortly afterwards. It’s worth noting that this child would not ordinarily have been vaccinated by this point.

One thing to note: It has been clearly confirmed by the coroner and other state health officials that the deaths were not fabricated, as RFK Jr. claimed.

The “Cause of Death” in Measles Cases

RFK Jr. said the coroner had no record of any “measles deaths,” but this is misleading on its own. In fact, most deaths from measles do not list measles as a primary cause of death. Instead, the primary cause of death is usually the specific complication leading to death. One study from the 1970s looked at this and found that only 9.9% of 454 cases actually listed “measles” as the primary cause of death.

Measles and the Spleen

Since details are only available in one case, the focus has been on that child. The coroner claimed that measles didn’t contribute to the death, because the spleen was not enlarged [3]. However, vaccine expert Dr. Paul Offit noted that this is hard to determine after a rupture, and such a rupture should have a clear explanation. This has not been settled yet.

It’s worth noting that an enlarged spleen is a known complication of measles, present in one third of all cases in a recent Polish study and 15.4% of all infant cases.

Overall, these cases were not fabricated. That said, health officials could have avoided a lot of confusion by being clearer in the way the cases were reported.

From [4]. A table showing the recorded cause of death in the cases covered by the study. Over 87% of cases were ruled due to respiratory and/or neurologic causes, not "measles."
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RC Yu17 days ago
vaccines

Autism rates probably not rising

Thought this study (a systematic review) deserved its own post. The review concluded:

About one in every 100 children worldwide is diagnosed with autism, and this number has gone up over time, mostly because people are more aware of autism and better at identifying it.

The review covered:

71 studies from 34 countries ... covering 99 different estimates of autism prevalence.

(Quotes from the Credo summary or the study.)

The point is, we aren't actually facing spike in autism -- whether due to vaccines or otherwise.

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Lee Johnsona month ago
vaccines

Claim: There is No Study Showing that Children Were Protected by the COVID Vaccine

Verdict: False and misleading

“Do you think that the COVID vaccine protected children? [...] Can you show me one study ... that shows that children were protected by the COVID vaccine? [...] that it did more good than harm to children. Can you show me one study that shows that?”

RFK talks vaccines, measles in interview with CNN's Dana Bash – RFK Jr. (from 7:25)

In his recent interview with CNN, RFK Jr. implicitly claimed – via a series of pointed, “gotcha” questions – that there were no studies showing that the COVID-19 vaccine protected children. Explicitly asking about proof “it did more good than harm,” he argued that there is no overall benefit to vaccinating children.

Is he right?

There is Plenty of Evidence that the COVID Vaccine Protects Children

RFK Jr. is absolutely incorrect to imply that no such evidence exists. While most people cannot pull a citation out of their heads on command, that isn’t the same as showing no evidence exists.

A systematic review of such studies was published in JAMA Pediatrics in 2023. It includes data from 15 observational studies and 2 randomized controlled trials focusing on children aged 5 to 11. The total number of participants was almost 11 million vaccinated and over 2.6 million unvaccinated children.

Among other things, this study found a lower risk of any COVID infection (53% reduction), symptomatic COVID infection (47% reduction), hospitalisations due to COVID-related illnesses (68% reduction) and multisystem inflammatory syndrome in children (95% reduction). It also found a 92% increase in the risk of adverse events, but only a non-significant increase in the risk of adverse events that prevent normal daily activities. 

What He Might Have Meant: The Risk of Myocarditis

This study did find the well-known risk of myocarditis following vaccination in younger people. However, this amounted to 1.3 cases per million after a first dose and 1.8 per million after a second dose.

Of course, this is not something to discount because of low incidence: it’s a legitimate concern.

However, this risk has to be compared to the risks following COVID infection, which is less likely in vaccinated children. A study from the UK found that there was an increased risk of myocarditis or pericarditis in the first 6 months after vaccination (in young people aged between 5 and 18), but noted that the risk is even higher after COVID infection.

Even without considering other risks (see images), it’s clear that the COVID vaccine is safer than COVID itself, even for myocarditis in young people.

From reference [2]. Forest plot showing the results of the meta-analysis. All analyses related to COVID infection and the severity of the condition favoured vaccinated children.
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Lee Johnson20 days ago
autism

Claim: Autism Prevalence Has Exploded, and We’re Not Just “Noticing It More”

Verdict: Largely false and misleading

“In 1970, the biggest epidemiological study at that time in history was performed [...] they were looking for autism, and they knew what autism looked like. And they came back with an incident rate of 0.8 per 10,000. So less than in 1 in 10,000. The rate, according to CDC today in this country, is one in every 31 children. [...] One of the talking points [...] is, oh, we're just noticing it more. But this is an absurdity.”

Trump signs executive order on childhood vaccines(from 7:10)

– RFK Jr

During the signing of an executive order on vaccines, one point made by both RFK Jr. and Trump about autism prevalence is very common: is there something weird going on with the increasing rate of autism?

What the Study RFK Jr. is Referencing Actually Says

RFK Jr. mentions this study specifically. As he said, it was released in 1970 and involved around 900,000 children in Wisconsin.

The study looked at the DSM-II entry for “childhood schizophrenia,” and notes three groups of cases:

  • A) What they call “classic” infant autism. This included an early onset, a desire for “sameness,” withdrawal and speech problems.

  • B) These children had some of the classic autism symptoms but the onset was later.

  • C) Likely psychosis with some complicating factors making diagnosis difficult.

RFK Jr. slightly misquotes the results for group A. Their prevalence was 0.7 cases per 10,000 children. Including group B would raise this to around 2.4 per 10,000. He also incorrectly implies the authors screened all 8-year olds in the state, but this is incorrect. They found cases from existing records from healthcare facilities for kids aged 3 to 12.

 It is true that a recent CDC estimate puts the figure at 1 in 31, based on modern diagnostic criteria (ICD-9 or 10). The modern DSM edition is V.

What’s Really Happening

You may have noticed that group B above would likely be just considered on the autism spectrum today. The differences between the 1970 diagnostic criteria and modern ones are hard to overstate, now encompassing Asperger’s syndrome, Rett’s disorder and others, and clearly differentiated from schizophrenia.

Despite RFK’s assertion, studies suggest that these changes, increased awareness and more effective screening are responsible for (at least) most of the apparent rise in diagnoses. For instance, previously under-represented groups like women and non-white people have a sharper rise in diagnoses.

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Lee Johnsona month ago
vaccines

Claim: The Phrase “Vaccines Do Not Cause Autism” is Not Supported By Science

Verdict: False and misleading

“The phrase ‘Vaccines do not cause autism’ is not supported by science.”

RFK, Jr.  

The CDC quietly updated its page on the link between vaccines and autism this week. Of note, it argues – like RFK, Jr. did in the quote above – that it is not an evidence-based claim to say “vaccines do not cause autism.”

But, is it?

There is No Evidence That Vaccines Cause Autism

Studies consistently show that specific vaccine-related concerns about autism – the Measles-Mumps-Rubella vaccine (MMR), thimerosal and mercury – are not linked to the condition.

Addressing Specific Claims from the CDC: Aluminium and Certain Vaccines

The CDC’s edited page contends that some vaccines (DTaP, Hib, HepB, IPV and others) have not been studied adequately with regards to autism. It also points the finger at aluminium in vaccines.

It is broadly true that these vaccines have not been studied specifically with regards to autism. However, one study looked at 42 neuropsychological outcomes at ages 7 to 10 based on vaccines received in the first year of life, including many mentioned by the CDC. It found no adverse effect from the full, timely vaccine schedule vs. receiving fewer vaccines or less frequently.

For aluminium, the CDC criticises a Danish study on over 1.2 million children which found no link between autism or any of 49 other conditions and cumulative aluminium exposure from vaccines received up to age 2. The CDC’s criticism simply cherry-picks figures from the supplementary material (see attached picture): it does not invalidate the result.

What “No Evidence” Really Means

One of my favourite scientific papers of all time finds that “the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials.”

So, is it reasonable to say the protective effect of parachutes “is not supported by science”?

Of course it is not. The key to understanding why is mechanism. If there is a mechanism – in this case, well-understood physics – we do not need systematic study to make a valid claim.

Conversely, if there is no science-based mechanism – as with vaccines and autism – we do not need specific studies to rule it out. On the contrary, anybody making such a claim would need to present actual evidence, rather than simply point to the absence of specific studies.

From reference [4], supplementary material. The CDC points to a single result - the increased risk for asperger's syndrome for people receiving vaccines from 2007 to 2018 - and yet discounts all of the other results for neurodevelopmental outcomes. This is a textbook example of cherry picking.
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Lee Johnson2 months ago
public health

Claim: There Are Cyclospora Outbreaks Every Summer

Verdict: True, but highly misleading

“First of all, there are Cyclospora outbreaks every summer. [...] Now that we know the probable culprit, I think it’s going to be much easier for people to make healthy choices.”

RFK Jr., July 17th, 2026 (Relevant question at 7:57)

As the outbreak of cyclosporiasis cases continues across multiple states in the US, RFK Jr. took to the Ryan Gorman Show to promote his push for healthier hospital food. At the end of the interview, in response to a question about the Cyclospora outbreak, he downplayed it, noting that there are outbreaks every summer.

But is this true?

There Are Cyclospora Outbreaks Every Summer...

The core of RFK Jr.’s claim is correct: there are Cyclospora outbreaks in the US every year.

Data from CDC Wonder confirms this simple fact. For instance, in 2022, there were 3,091 cases, largely as a result of contaminated leafy greens. Likewise, the database shows outbreaks of thousands of cases in all recent years.

 ...But This One is Much Bigger

Despite being technically true, RFK’s comment drastically underplays the current outbreak by creating a sense of equivalence with previous outbreaks. This is highly misleading.

The CDC reports that as of July 14th, there are 1,645 lab-confirmed domestic cases, and notes that there are 5,100 further cases that need to be tested for domestic origin. Note that the lab-confirmed domestic cases so far are already over half of the total for the entire year of 2022. The CDC also notes that by this time in 2025 there were only 249 reported cases – less than one-sixth of the current number.

Data going back to 1990 shows how the situation has developed over time. Most years, there were fewer than 100 cases. Notable exceptions include 1996 (1,646 cases), 1997 (1,594 total cases), 2005 (692 total cases) and 2015 (546 cases).

The outbreaks do appear to be getting bigger, generally speaking. Data from CDC Wonder for 2017 to 2023 [2] show between 1,000 and 4,700 cases per year, peaking at 4,703 in 2019, declining in 2020 and 2021, before climbing to 4,463 in 2023.

However, even data for Michigan alone show 5,002 cases so far in 2026.

In summary, it is highly misleading to equate the current outbreak with those experienced previously. The current outbreak is bigger than any in the past 36 years.

RFK Jr. points out that there are outbreaks of cyclosporiasis every year. However, even recorded cases in Michigan alone [5] far exceed numbers recorded for any year since 1990.
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Lee Johnson2 months ago
public health

Claim: Seed Oils Are a Driving Cause of the Obesity Epidemic (and Beef Tallow is Better)

Verdict: False and highly misleading

“Seed oils are one of the driving causes of the obesity epidemic. Interestingly enough, this began to drastically rise around the same time fast food restaurants switched from beef tallow to seed oils in their fryers.”

Fast Food is a part of American culture. But that doesn’t mean it has to…

One of RFK Jr.’s long-running beliefs is that seed oils are a huge problem for society, and his comments have contributed to many restaurant and fast food chains moving away from seed oils. They often switch to beef tallow, which RFK’s nostalgia-drenched tweet also suggests is better.

But is seed oil really that bad? And is beef tallow better?

Why We Moved Away from Beef Tallow

Beef tallow (rendered cow fat) was more common historically, but the move to seed oils was primarily driven by concerns about cholesterol. As a recent JACC Advances editorial points out, beef tallow is high in saturated fat, and studies show that consuming beef tallow raises low-density lipoprotein cholesterol more than olive oil or corn oil.

It concludes that no evidence supports the idea that beef tallow is a healthier alternative to seed oils.

Do Seed Oils Cause Obesity?

There aren’t actually too many studies looking at this issue, but one systematic review and meta-analysis looked at 42 studies that addressed edible oils and weight gain. It found evidence that soybean, sunflower and rice oil were associated with the most weight gain, and generally that sesame and canola oil are linked with weight loss.

There are methodological issues, though. Notably, many studies didn’t account for overall calorie intake, and they often didn’t mention specific amounts of oil consumed either.

However, other reviews have also reached the same conclusion: some seed oils may actually reduce weight. And more importantly, large cohort studies strongly suggest that consumption of plant-based oils (including seed oils) reduces mortality compared to high-cholesterol options like butter. 

Why Seed Oils Look Bad for Obesity

So why the focus on seed oils? Simply, many unhealthy foods use seed oils, and seed oil consumption has increased alongside obesity rates. But correlation is not causation. You simply can’t ignore everything else we eat. If you’re at McDonald’s every day, it doesn’t really matter which oil they use.

Many aspects of American life have changed since RFK Jr.’s nostalgic beef tallow days. Bringing back the tallow won’t change those back too.

From reference [4]. The study shows that most oils have no impact on weight gain, accounting for other variables. In this image, blue represents no effect, green represents a beneficial effect and yellow represents a detrimental effect. Full table available in the study.
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Lee Johnson2 months ago
vaccines

Claim: No Current Vaccines (Except COVID) Were Safety Tested Against Placebo Before Approval

Verdict: False and misleading

"There are placebo-controlled trials, senator [...], under the current vaccine schedule, none of the vaccines – with the exception of COVID – have ever experienced a safety trial, pre-licensure, that involves an inert placebo. None of them."

"They do have efficacy tests against placebo, but they don't have safety testing"

RFK Jr., September 2025

WATCH: RFK Jr. clarifies stance on placebo trialsAmid RFK Jr.’s behind-the-scenes push to link vaccines to various illnesses, attention is turning back to his previous claims about placebo-testing vaccines. He made this argument at length in a 2023 book, Vax-Unvax: Let the Science Speak, and had to clarify his views to a Senate subcommittee last year.

While he said he didn’t want to re-test all vaccines against placebo, he did claim that only the COVID vaccine was safety tested against placebo before being approved. But is he right?

Why We Don’t Placebo-Test Most Vaccines?

We don’t usually conduct placebo controlled testing of most vaccines because that would mean exposing people to risk by denying effective treatment. Vaccines are generally tested against the current best care, which likely means an older vaccine. But in cases where vaccines are new and there is no existing treatment, tests are placebo-controlled.

The Polio Vaccine Trial

The most famous example of a controlled trial for a vaccine comes from the 1954 test of Jonas Salk’s polio vaccine. Although it did have methodological problems, 650,000 children were randomized to receive either the polio vaccine or a placebo. Not only did the vaccine work, safety monitoring found that only 0.4% of vaccinated children had minor reactions, and this was about 100 times the rate of serious reactions.

Other Placebo-Controlled Vaccine Safety Studies

There are many other examples.

In January 2006, around 68,000 infants were randomized to receive either the rotavirus vaccine or an inert placebo. Not only was the vaccine effective, risks were similar to placebo. The vaccine was approved later that year.

Between 2002 and 2003, the HPV vaccine was tested in over 12,000 women, who received either the vaccine or the placebo at random. The study was published after the vaccine’s 2006 approval, but was conducted before. Again, the study found the vaccine to be both safe and effective.

Researchers have compiled a spreadsheet of such studies, which is linked in the comments.

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Lee Johnson2 months ago
vaccines

Claim: Retracted Paper “Cited Extensive Literature” Corroborating Link Between Vaccines and SIDS

Verdict: False and misleading

“The Miller paper cites an extensive literature on an association between sudden infant death syndrome (SIDS) and recent vaccinations, from 1933 to 2014.”

RFK Jr., via Twitter: I sent this letter to the Editor-in-Chief of Toxicology Reports demanding a full explanation for…

RFK Jr. wrote to the editor of Toxicology Reports about a now-retracted paper, as revealed by a social media post this week. He raised several points in his letter asking for “full transparency” regarding the journal’s decision to remove the paper.

Specifically, RFK Jr. claimed that the paper cited “extensive literature” corroborating the supposed link between vaccines and sudden infant death syndrome (SIDS). But did it?

The Paper and Why It Was Flawed

Author Neil Miller looked at reports from the Vaccine Adverse Event Reporting System (VAERS) on infants who died within 60 days of vaccination (doses between 1990 and 2019). He identified 2,605 such cases, and 1,048 specifically mentioned SIDS.

In this time, based on approximately 3,500 cases in the US per year, there would have been 105,000 SIDS cases in total. The paper thus covers about 1% of SIDS deaths.

He looked at the distribution of deaths relative to the day they were vaccinated, and compared it statistically to an equal distribution (i.e. pure chance). He found a difference.

The key problem is that VAERS is a passive database, which only captures cases which are reported to it. Appearing on the database doesn’t prove a link to vaccines, just that someone thought there was one. Is it surprising, then, that the 1% of SIDS cases believed to be vaccine-related should cluster around the vaccine date? Of course not. This is why the paper is deeply flawed.  

Does it Cite “Extensive Literature” Proving the Link?

RFK’s claim that it cites “extensive literature” corroborating the link is also incorrect. In fact, the author cites numerous case reports and some other analyses which do the same as the author: look at cases that occurred near vaccination, not that are caused by them. This issue has been identified by other authors . The cited studies cannot and do not prove the link exists in general.

The broader picture is captured by studies which look at large numbers of kids who receive a vaccine and their outcomes. One study did this for around 130k children in the 80s and found no link. Another paper from Britain used a case-control design [5] and actually found a protective effect of vaccines.

From Miller's retracted paper [2]. The graph shows that for the parents who submitted their SIDS case to the vaccine adverse event reporting system, they tend to have happened close to the date of vaccination. We must ask: why else would you submit it there? Paper still online here: https://pmc.ncbi.nlm.nih.gov/articles/PMC8255173/
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Lee Johnson3 months ago
measles

Claim: Vitamin A Drastically Reduces Measles Mortality

Verdict: Partially true, but misleading

“Studies have found that vitamin A can dramatically reduce measles mortality.”

“By 1960 -- before the vaccine’s introduction -- improvements in sanitation and nutrition had eliminated 98% of measles deaths. Good nutrition remains a best defense against most chronic and infectious illnesses. Vitamins A, C, and D, and foods rich in vitamins B12, C, and E should be part of a balanced diet.”

ROBERT F. KENNEDY, JR.: Measles outbreak is call to action for all of us

Last week, reports revealed that RFK Jr. is looking to access Americans’ medical records to investigate the causes of “chronic childhood disease,” which many commentators suspect is linked to his views on vaccines. But if he’s gearing up to criticize vaccines, what’s his alternative?

Early in the measles epidemic, he took to Fox News to imply that vitamin A is a valuable treatment and – potentially – even a preventative. But was he right?

Vitamin A Reduces Measles Mortality Risk (Sometimes)

A Cochrane Review addressed exactly this issue, looking at studies on vitamin A and measles mortality. In fact, this was indirectly cited by RFK Jr. in his Fox News opinion piece. With eight trials included (n = 2,574), the review concluded that vitamin A dosing did not lead to a significant decline in mortality risk.

However, more fine-grained analysis revealed that while one dose was not effective, children under 2 years of age did see a reduction in risk after 2 doses of vitamin A.

Broadly, RFK Jr. is correct – vitamin A can help.

Where the Data Falls Short

There is a problem, though. As a comment piece in the Lancet argues, the reduction in mortality in these studies is likely dependent on where the study took place. In many places in the world, vitamin A deficiency is common, and measles tends to have much higher mortality rates in these places. Most of the studies were conducted in countries with these issues.

In the US, however, vitamin A deficiency is rare (less than 1 percent), so vitamin A treatment may not help as much. In fact, study in Italy from 2021 found no difference in measles outcomes after vitamin A treatment. When deficiency isn’t an issue, the benefits seem to disappear.

Does Vitamin A Prevent Measles?

No. It is true that nutrition can impact the efficacy of the measles vaccine, but vitamin A itself has no preventative effect whatsoever.

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