Journalist Alex Berenson misrepresents German study on COVID-19 mRNA vaccination

At the end of March 2025, journalist Alex Berenson published a Substack post claiming that a German study showed COVID-19 mRNA vaccines changed “a crucial part of the macrophage chromosome called the histone” and that these changes are “linked to cancer and autoimmune disorders”. He also shared it on X, where it gained more than 600,000 views.

His post was later picked up by the anti-vaccine organization Children’s Health Defense, which rehashed the same claim in its publication The Defender.

Berenson became a notable source of health misinformation during the COVID-19 pandemic. Science Feedback reviewed several of these claims and found them to be inaccurate, misleading, or unfounded. Despite lacking the relevant qualifications (Berenson has no scientific or medical training), his Substack has drawn more than 240,000 subscribers to date.

His claim about the German study, like many of his earlier claims, is inaccurate and misrepresents the study’s findings. We explain below.

Histones and gene regulation

To understand the problem with Berenson’s claim, we first need to understand what histone modifications and their effects are.

Histones are proteins around which DNA is tightly coiled. The DNA and histone complex is collectively known as a nucleosome; nucleosomes in turn are the basic structural unit of chromatin. As Figure 1 below shows, the spatial arrangement of chromatin regulates gene activity by regulating transcription—the production of RNA based on DNA.

Figure 1 – An illustration depicting the role of histones and how histone modifications—small chemical changes on histones—can control gene expression by opening and closing chromatin, thereby regulating the transcription machinery’s physical access to DNA. Source: U.S. National Human Genome Research Institute.

Transcription is key to gene expression, as it controls how much RNA is made, which in turn controls how much protein is made and consequently affects protein activity. Protein activity in turn controls biological activity. When chromatin is closely packed together, transcription cannot take place, since the protein machinery needed for transcription cannot physically access the DNA.

Thus the opening and closing of chromatin has ramifications for biological outcomes. Chromatin opening and closing is mediated by small chemical changes to histones, for example by adding a methyl group (methylation) or an acetyl group (acetylation) to an amino acid that’s part of a histone.

The video below from the Feinberg School of Medicine at Northwestern University provides a simple visualization of how different histone modifications affect gene expression.

Because these changes to gene expression are independent of the genetic instructions encoded in DNA, unlike mutations, they are also known as “epigenetic” changes (meaning “beyond genetics”). Histone modification is just one of several types of epigenetic modifications; other types of changes, like DNA methylation, also exist.

It’s important to be aware that epigenetic changes aren’t intrinsically good or bad. On the contrary, their biological effects depend heavily on the context, for instance, the gene or the type of cell they affect, or the biological condition of the affected cell. Therefore, sweeping statements about an epigenetic modification’s harm (or benefit), as we observe in Berenson’s Substack post, should always be viewed with skepticism.

What did the study do?

The study cited by Berenson, titled “Persistent epigenetic memory of SARS-CoV-2 mRNA vaccination in monocyte-derived macrophages”, was led by a group of scientists in Cologne, Germany^[1]. It explored the potential effects of COVID-19 mRNA vaccination on immune memory, or the ability of the immune system to recognize and quickly neutralize a previously encountered pathogen. Immune memory can be established by infection or vaccination and forms the bedrock of long-term protection against a disease.

The authors were curious about how a particular group of immune cells, called macrophages, might contribute to immune memory. To study this, they derived macrophages from the blood samples of mRNA-vaccinated individuals taken before vaccination and at various points in time after vaccination. They then tested the macrophages’ response to various danger signals associated with infection (known as pathogen-associated molecular patterns and danger-associated molecular patterns).

They observed that two weeks after the second vaccine dose, macrophages released more of a cytokine called interleukin-1β relative to macrophages derived from the pre-vaccination period.

Because the release of interleukin-1β is associated with inflammation, which is a normal response to infection, these results suggested that SARS-CoV-2 vaccination “primes” or prepares macrophages to respond quickly to immunological triggers, even if those triggers were unrelated to the virus SARS-CoV-2.

These findings led the authors to question what changes might have facilitated the increased response to danger signals. Based on earlier observations by other research groups, which found that epigenetic modifications were linked to enhanced immune response to danger signals, the authors decided to examine epigenetic markers in macrophages post-vaccination, specifically H3K27ac, short for histone 3 lysine 27 acetylation.

H3K27ac is, broadly speaking, an epigenetic marker associated with increased transcription activity. As we explained earlier, increased transcription activity isn’t inherently bad (or good, for that matter); its ramifications depend on context.

In this particular circumstance, H3K27ac was associated with the establishment of immune memory. These modifications persisted in various regions in the genome, even 34 weeks after the second vaccine dose, and tended to cluster around immune-related genes, such as those related to the activation of the immune system.

In brief, the study illustrated that COVID-19 mRNA vaccination can stimulate lasting innate immune memory by inducing epigenetic changes in immune cells. The authors concluded:

“The dynamic aspects we observed for epigenetic reprogramming of classical innate immune cells may have implications for the improvement of vaccine responses and designs, the overall immune response towards non-related infections and even our understanding of post vaccination inflammatory diseases which occur in a small number of vaccinated individuals.”

Berenson’s post contains faulty associations, failed to account for biological context

In an email to Science Feedback, Jan Rybniker, one of the study’s senior authors, stated that “There is no link between COVID-19 vaccines and cancer” and called the claims spread by Berenson “false information and dangerous misinterpretations of our research data”.

Berenson’s chief argument in his Substack post is that other scientific publications reported finding associations between H3K27ac and certain cancers. Based on this, he concluded that the study’s findings meant COVID-19 mRNA vaccination would cause changes leading to cancer.

This is an example of a logical fallacy known as faulty generalization. In other words, Berenson assumed that because H3K27ac is a modification that’s been implicated in cancer, any H3K27ac modification must therefore also be cancer-related. This type of fallacy tends to occur when a person has only an incomplete knowledge of the topic at hand, or if they opt to cherry-pick evidence, accepting only those that favor their point of view while dismissing conflicting evidence.

It’s true that in some contexts, H3K27ac modification is related to cancer development^[2]. But in other contexts, H3K27ac modification contributes to beneficial effects. As we explained earlier, the study illustrated how H3K27ac modifications contributed to the establishment of immune memory. We also found another study that reported how H3K27ac modifications in certain immune cells could produce anticancer activity^[3].

Thus, the effects of H3K27ac modification are complex and nuanced, in contrast to the simplistic depiction in Berenson’s post.

Berenson’s claim parallels other faulty generalizations, such as the incorrect idea that cancer patients should avoid sugar because cancer cells feed on sugar—ignoring the fact that healthy cells also require sugar to function.

He also claimed that the authors “avoided” suggestions that mRNA vaccine-induced changes could affect bone marrow stem cells and cause leukemia (a type of blood cancer).

But that’s inaccurate, as the authors acknowledged the possibility that epigenetic changes in bone marrow stem cells could have contributed to the macrophage changes they observed. Quote: “Similar findings were recently made for SARS-CoV-2 infections which trigger long-lasting epigenetic and transcriptional modifications in macrophages, monocytes and hematopoietic stem and progenitor cells (HSPC) […] Thus, it is conceivable that macrophages of vaccinated or infected individuals may respond in a similar way toward viral infections other than the target disease.” [emphasis added]

Finally, the study didn’t make any observation pertaining to leukemia or cancer in general.

The authors did postulate that their findings might have relevance to “post vaccination inflammatory diseases which occur in a small number of vaccinated individuals”, something that Berenson also pointed out. But he omitted the fact that the authors also considered the other side of the coin: that “the broad and non-discriminative innate immune response we observed in macrophages following SARS-CoV-2 mRNA vaccination may induce resilience programs against other, non-related infectious diseases”.

In summary, Berenson’s post misrepresented the study’s findings and appeared to engage in cherry-picking when it came to framing the study, presenting only the negative takeaways while failing to inform readers of the potential upsides.

Conclusion

The claim that a German study found COVID-19 mRNA vaccines caused epigenetic changes that increase cancer risk is false. It misrepresents the study’s findings, which looked at how histone modifications in macrophages could play a role in lasting immune memory. The findings could also have implications for immunity to infections that are unrelated to COVID-19 and inflammatory disorders that occur post-vaccination. However, more research is still needed before we can draw reliable conclusions about either outcome.

REFERENCES

• 1 – Simonis et al. (2025) Persistent epigenetic memory of SARS-CoV-2 mRNA vaccination in monocyte-derived macrophages. Molecular Systems Biology.
• 2 – Zhu et al. (2024) A narrative review of epigenetic marker in H3K27ac and its emerging potential as a therapeutic target in cancer. Epigenomics.
• 3 – Wu et al. (2024) Neutrophil profiling illuminates anti-tumor antigen-presenting potency. Cell.