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Home » Joe Mercola falsely claims COVID vaccine boosters cause cancer

Joe Mercola falsely claims COVID vaccine boosters cause cancer

Last updated on February 7th, 2023 at 02:29 pm

On Robert F Kennedy Jr’s awful website, The Defender, the quack Joe Mercola writes that the COVID-19 vaccine boosters cause cancer. Seriously, he wrote that.

The article is filled with a metric tonne of false claims, but I want to just focus on cancer since that’s the basic claim made by Mercola. If I spent all of my typing skills writing a 25,000-word post about every false claim made by this quack, I would be exhausted.

So, let me get to it.

COVID vaccine boosters cause cancer

Mercola starts his whole tirade by saying, “Research shows the SARS-CoV-2 spike protein obliterates 90% of the DNA repair mechanism in lymphocytes, white blood cells that help your body fight infection and chronic disease, including cancer.”

I’ll start right at the top and say that not only is there no clinical evidence for this, but there also isn’t even a case to be made for biological plausibility. So, I’m going to break my takedown of Mercola’s, and by association, Robert F. Kennedy Jr’s, false claims about the COVID-19 vaccine booster and cancer. The first part will look at the clinical evidence that establishes a link. The second will examine whether the COVID-19 vaccine and its boosters could cause cancer by some novel or known mechanism.

I could get lazy and write “no” for each section, but I think you want more. So here we go.

white and red dandelion flower
Photo by Daniel Dan on

Clinical evidence

Well, there simply is no clinical evidence of a link between the COVID-19 vaccine booster and any cancer (and remember, there are over 200 different cancers). None.

There are several reasons for this:

  1. Cancer doesn’t usually rear its ugly head for decades after a causal event (say cigarette smoking). We would have to set up a double-blinded, randomized clinical trial of a vaccinated vs. unvaccinated group, then check back with both arms of the study annually for decades. Now, as I have written before, this type of study would be unethical and immoral, because the placebo group would be put at risk of getting COVID-19. And no, anti-vaxxers could not volunteer for the placebo group because then the study is no longer double-blinded nor randomized. Thus, I doubt we’ll ever see a clinical trial that will do this study because of time and ethics.
  2. A proper study will be what I call an “epidemiological” study, such as a case-control or cohort, which would divide up a large group of individuals that have known vaccination statuses, then, decades out, determine if there’s a difference in cancer rates between the groups. Alternatively, we could divide up the groups into cancer and non-cancer populations, and check the vaccination statuses of each. These types of studies have not been done, because there just aren’t any cancer signals with vaccines.
  3. The claim that there has been an increase in the number of cancers in the USA is just patently false. The estimated incidence of all cancers in 2019 was about 5.38 per 1000 individuals and 5.76 per 1000 individuals in 2022. This negligible uptick in cancer incidence was mostly driven by a huge increase in prostate cancer incidence (which I need to explore further someday). Now, both of these numbers are estimates, since we won’t have data on 2022 cancer numbers for at least 2-3 years.

Unless Mercola has a magic ball that gives him cancer numbers, there is just no evidence whatsoever that has shown that there is an increase in cancer risk during the pandemic.

Mercola also claims that “cancer rates have increased since the introduction of the COVID-19 shots and are now one of the top three leading causes of premature death among younger adults.” That would be well and good, but there is just no reliable evidence that there is an increase in cancer numbers among “younger adults.” Again, these numbers won’t be available for years, and cancer is not in the top 3 causes of death.

The leading causes of death for young adults, aged 25-34, is, in order:

  1. Poisoning (I was actually surprised by this)
  2. Suicide (not surprised)
  3. Automobile accidents
  4. Homicide
  5. COVID-19
  6. Liver disease
  7. All cancers

In other words, cancer ranks only seventh on the list of causes of death in young adults. I don’t know what magic ball Mercola uses to get his claims, but they are unsupported by facts.

Mercola also states that “the leading causes of death in 2021 were heart disease and cancer, both of which are potential side effects of the COVID-19 jabs.” Does he think his readership is stupid? Don’t answer that, because all of us aren’t.

According to the CDC, the leading causes of death in the USA are cardiovascular disease (that’s everything from heart attacks to strokes), cancer, and COVID-19 in 2021 (the most recent data available). In 2020, well before vaccines were available, the leading causes of death were cardiovascular disease, cancer, and COVID-19. In 2019, before the pandemic and COVID-19 vaccines, the CDC reported that the leading causes of death were cardiovascular disease, cancer, and accidents (non-intentional death is the definition from the CDC).

So, there is no sudden increase in cancer mortality over previous years. This is a ridiculous claim, but Mercola shouts that cancer is in the top three (shocking news, I know), and he immediately blames the COVID-19 vaccine and its boosters.

I think I’ve done enough here. There is simply no evidence that the cancer rate or mortality (along with cardiovascular disease rate and mortality) has sharply increased since the introduction of COVID-19 vaccines. None.

Yes, the average life expectancy of Americans has decreased significantly, but that number is almost totally a result of the COVID-19 pandemic. There has not been an increase in the risk of cancer or cardiovascular diseases since the beginning of the pandemic (as best as we can tell since most numbers are estimates now). Mercola is just pulling numbers out of his digestive tract and hoping no one notices.

The claim that excess deaths are caused by COVID-19 vaccines

Mercola and RFK Jr keep pushing the nonsense that there are thousands or even millions of deaths and other harms, such as myocarditis, caused by the COVID-19 vaccine and its boosters. I have debunked this dumpster diving into VAERS (Vaccine Adverse Events Reporting System). And others have too.

If there were a sudden increase in thousands or millions of deaths from the COVID-19 vaccine, we’d notice it in statistics for deaths over the past couple of years. The only excess deaths that we are observing are from COVID-19 itself. Take that out of the equation, and the mortality figures are barely different than what we observed in 2019, before the pandemic and COVID-19 vaccines.

Let’s get back to cancer.

Mercola invents a mechanism for COVID-19 vaccine and cancer

As I wrote before, science-based medicine requires both clinical data supporting a cause and effect, but it also requires a biologically plausible mechanism. This is the same method as establishing that correlation infers causation.

Anti-vaxxers love to “prove” a biologically plausible mechanism for a side effect without any supporting clinical data. Anti-vaxxers will claim that aluminum in vaccines causes autism, but there is no clinical or epidemiological evidence at all that vaccines are linked to autism. Or they try to claim that the HPV vaccine causes autoimmune diseases through some mysterious mechanism when numerous large studies have shown there is no link between the vaccine and any autoimmune disease.

So, despite the utter paucity of clinical or epidemiological evidence supporting the claim that the COVID-19 vaccine booster causes cancer, Mercola tries to prove that there is a link by stating that “research shows that SARS-CoV-2 spike protein obliterates 90% of the DNA repair mechanism in lymphocytes, white blood cells that help your body fight infection and chronic disease, including cancer.”

Wow, if that were true, it would be Nobel Prize-winning science. So I started to dig into this, and you’ll find it amusing where this leads.

  1. Mercola links to this unscientific article published in a click-bait website called The Exposè that supports his claim. This website, as far as I can tell, is filled with junk science about vaccines. Of course.
  2. So I read that article, and I try to find a link to where they get their data. Nothing. I had to spend an hour to find this article.
  3. And, no surprise to those of us who have been doing this for a long time, the article was retracted. OOPS!

So, Mercola’s basic point that the spike protein destroys the DNA repair system is based on a retracted paper that essentially doesn’t exist. Why was the paper retracted? Here’s what the editor wrote:

Both the chosen construct of the spike plasmid that contained a C-terminal fused with 6xHis tag and use of a GFP reporter system under overexpression conditions in the protocol were identified as having the potential to introduce significant ambiguity regarding the nature of the reported observations. The reliability of the results and conclusions presented have therefore been undermined. Furthermore, statements regarding the effect of the spike protein on the adaptive immunity are misleading as in this article no experiments related to the adaptive immunity were performed, and the full-length spike-based vaccine was not studied. Therefore, conclusions related to vaccine safety are not validated and lacked experimental support. This article [1] is retracted and shall be marked accordingly. This retraction was approved by the Editor-in-Chief of the journal Viruses.

To get down to the essentials, the actual spike protein from an mRNA vaccine was not actually studied, and the relationships to vaccine safety were not supported by their flawed research. They had no experimental support for their claims. Again, in the world of science, this study no longer exists.

Now, I’m sure that Mercola and RFK Jr are going to claim that jackbooted police from Big Pharma forced the editor of the Viruses journal to retract it. Or that the reptilians are in control of the journal and they had to suppress this study.


So, let’s review everything. There is no evidence that cancer incidence or mortality has increased since the COVID-19 vaccine and its boosters were released. And there is no evidence of a mechanism by which the vaccine could cause cancer.

In other words, Mercola has nothing.


Michael Simpson

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