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No research shows that COVID-19 vaccines promote cancer in people; study cited as evidence tested the spike protein from the virus in laboratory cells

Inadequate support: The claim relies on a study that used cells grown in the laboratory to produce the spike protein from the SARS-CoV-2 virus. These experimental conditions don’t reflect what happens with the COVID-19 vaccine in the human body. Therefore, the results from this study can’t be extrapolated to people who received a COVID-19 vaccine.
COVID-19 vaccination reduces the risk of COVID-19 hospitalization and death and is particularly important for people who are at a higher risk for severe COVID-19 complications. These include people with cancer and other conditions that can weaken the immune system. There is currently no evidence suggesting that COVID-19 vaccines increase the risk of cancer, make it more aggressive, or make cancer therapy less effective.



On 1 July 2024, the group America’s Frontline Doctors posted a Facebook reel claiming “SPIKE PROTEINS FROM COVID SHOTS COULD PROMOTE CANCER GROWTH”. The reel was viewed more than 400,000 times.

America’s Frontline Doctors became widely known in 2020 for promoting the antimalarial drug hydroxychloroquine to prevent and cure COVID-19, despite a lack of evidence for its efficacy. The group continued to spread COVID-19 misinformation throughout the pandemic. In 2022, its founder Simone Gold was sentenced to 60 days in prison for entering the U.S. Capitol during the 6 January 2021 riot.

Claims linking vaccination with cancer have thrived on social media since the COVID-19 vaccines became available. However, such claims are unsubstantiated, often based on anecdotal accounts and misinterpreted data. The Facebook reel is yet another example of such a claim.

The reel’s claim is based on a study by Shengliang Zhang and Wafik S. El-Deiry, oncology researchers at Brown University, published in Oncotarget in June 2024. El-Deiry previously amplified unfounded claims that COVID-19 vaccines cause “turbo cancer”. Science Feedback debunked similar claims in earlier reviews.

Zhang and El-Deiry found that cancer cells modified to produce the SARS-CoV-2 spike protein showed changes in p53, a tumor suppressor protein. However, the study was done in cancer cells growing in the lab, not in humans. Moreover, the experiments involved the spike protein from the virus, not from the vaccine. Therefore, these results don’t provide evidence of what happens in people who received a COVID-19 vaccine, which makes the reel’s claim unsupported.

Science Feedback reached out to El-Deiry for comment regarding the reel’s claim. In an email, he stated that all the limitations of the study were acknowledged in the publication. Below, we discuss these limitations in greater detail.

What did the study show?

The study aimed to investigate the effect of the spike protein of SARS-CoV-2 on the p53 protein.

To do this, the researchers modified human lung, breast, colorectal, and sarcoma cancer cells grown in the lab to produce the SARS-CoV-2 spike protein.

p53 is a well-known tumor suppressor protein, meaning it helps protect the body from uncontrolled cell growth. Specifically, p53 is commonly dubbed “the guardian of the genome” due to its essential role in regulating DNA repair, cell division, and programmed cell death (apoptosis).

p53 is generally inactive until something damages the cell DNA, such as a toxic chemical or ultraviolet rays from sunlight. This damage activates p53, which then instructs the cell to repair the damage, or if this isn’t possible, to stop dividing and self-destruct. In short, p53 prevents damaged cells from accumulating, dividing uncontrollably, and potentially developing into tumors.

The study found that spike protein-producing cells showed changes in p53 function compared to cells that didn’t produce the protein. When the researchers exposed these cells to the chemotherapy drug cisplatin, they observed that the drug caused damage but the cells were less responsive to it compared to cells that didn’t produce the spike protein. This was also associated with slightly increased survival of cancer cells, suggesting the drug was killing fewer cells than expected.

Based on these results, the authors speculated that SARS-CoV-2 might reduce the natural barriers that prevent the cell from developing into a tumor, particularly after repeated SARS-CoV-2 infections. They added that this potential mechanism might be relevant “in the context of viral infection and mRNA vaccines in general but also for patients with cancer who may be receiving cytotoxic or other cancer treatments”.

Finally, the authors called for further investigating the impact of viral proteins like SARS-CoV-2 spike on cell DNA repair mechanisms. This, they argued, would help minimize the risk of interfering with this process when developing therapeutic strategies like vaccines.

While more than half of all cancers have mutations in TP53[1], research suggests that p53 malfunction in itself isn’t sufficient to cause cancer. Instead, cancer is likely the result of multiple, progressive genetic changes.

Referring to the research published in Oncotarget, El-Deiry, one of the study’s authors, talked about the complex role of p53 in cancer in an X/Twitter thread:

“Complete loss or mutation of p53 doesn’t cause cancer immediately either in mice or humans. Similarly HPV E6 takes years to cause cervical or head and neck cancer (and there’s an effective vaccine for HPV). These things are well known. But clearly loss of p53 is associated with cancer over time. It is a difficult area when one discusses ‘causes.’ It’s like cause of death. There’s an immediate cause but there can be many contributing factors.”

Results in spike protein-producing cells can’t be directly extrapolated to people who received a COVID-19 vaccine

The study suggests a potential mechanism by which the virus SARS-CoV-2 might interfere with DNA repair in the cell. However, these results are preliminary and only apply to the laboratory conditions used in this study.

First, all the experiments were done in cell cultures, which are very different from a whole organism like the human body. Cell cultures are a valuable initial model for studying biological mechanisms in a controlled and reproducible environment. However, they can’t simulate the complexity of a human body, which comprises multiple tissues and organs connected to each other. For this reason, the results obtained in cell cultures cannot demonstrate that the same phenomenon occurs in people.

Furthermore, the study only evaluated the effects of SARS-CoV-2 spike protein in cancer cells. These cells might have a different susceptibility to changes in p53 function compared to healthy cells. The authors acknowledged these limitations in the Discussion:

We have not conducted in vivo experiments and some of our experiments lack additional controls such as in flow analysis or by looking at kinetics of cell cycle checkpoint regulation. We have not evaluated normal cells such as airway, muscle, immune, brain or intestinal cells.” [emphasis added]

Second, the study evaluated the effects of the spike protein from the virus, not from the vaccine. From the Discussion:

“In the current manuscript we show preliminary evidence limited to viral protein spike from SARS-CoV-2 impacting on p53 function by inhibiting its transcriptional activation of key genes that mediate its functions in tumor suppression.” [emphasis added]

The spike protein from the virus and that induced by COVID-19 vaccination are very similar but not identical. Specifically, the vaccine-spike protein contains a mutation that stabilizes the protein and prevents it from fusing within the cell membrane as the viral protein does. Since the spike proteins from the virus and the vaccine are different, the results obtained with one might not hold true for the other.

To produce the spike protein, the researchers inserted the genetic material encoding this protein into a plasmid (a circular DNA molecule) that they transferred into the cells. This is an artificial process that results in high amounts of protein (overexpression) that can interfere with its normal function and even be toxic for the cells. This can cause effects that aren’t specific to the protein investigated but simply result from producing any protein in high amounts. However, the study didn’t control for this effect by assessing p53 function in cells overexpressing a protein unrelated to SARS-CoV-2.

Finally, the results suggested that cancer cells responded less to DNA damage and survived slightly better when they produced the spike protein. However, the study couldn’t establish “Whether these changes are a consequence from the suppressive effect of SARS-CoV-2 spike on p53 signaling”. In other words, the study didn’t show that the changes were actually caused by the spike protein interfering with p53.

The U.S. National Cancer Institute and the American Cancer Society state there is currently no evidence suggesting that COVID-19 vaccines cause cancer or make it more aggressive or recurrent. As we explained in earlier reviews, there is also no plausible scientific mechanism that could explain how COVID-19 vaccines cause cancer.

While this study suggested that SARS-CoV-2 spike protein could influence the activity of one tumor suppressor protein in cancer cells, it didn’t demonstrate that effect in people infected with SARS-CoV-2, let alone people who received a COVID-19 vaccine.



Published on: 10 Jul 2024 | Editor:

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