Claims that a study conducted by South Korean researchers “proves” a causal link between COVID-19 vaccines and an increased risk of up to six types of cancer have gone viral in recent days. These claims caused a wave of misinformation, with prominent figures and platforms using their professional titles to lend credibility to them.
So how did this happen?
Who claimed the study showed a link between vaccines and cancer?
Social media accounts cited a study titled “1-year risks of cancers associated with COVID-19 vaccination: a large population-based cohort study in South Korea”, published in Biomarker Research, an open access academic journal. The study used statistics from the South Korean health insurance database and found a pattern: individuals who received the vaccine were also more likely to be diagnosed with certain types of cancer within one year. This statistical correlation was quickly misrepresented as definitive “proof” of a direct risk.
A misinformation campaign focused on spreading specific, alarming numbers to stir panic, with influential figures using their professional credentials to amplify the message.
For instance, the platform Vigilant Fox, which defines itself as a media company founded by a “healthcare specialist turned independent journalist”, promoted the study, claiming it showed a 27 percent overall increase in cancer risk. It further listed exaggerated increases for specific cancers, such as a 53 percent rise in lung cancer and a 69 percent increase in prostate cancer.
COVID vaccines linked to a 27% INCREASE in overall cancer risk, South Korean study finds.
“There’s a one in a thousand chance that this result arose by chance,” Dr. John Campbell noted.@ChildrensHD reports:
The study used data from 2021-2023 for over 8.4 million people in… pic.twitter.com/kDZ56rCV6w
— Vigilant Fox 🦊 (@VigilantFox) October 6, 2025
Then, Nicolas Hulscher, MPH, who identifies himself as an “epidemiologist”, went further, falsely claiming that the vaccine increases the risk of “seven types of cancer”, linking the study to others without justification to assert that these cancers “all increased significantly after vaccination”.
🚨COVID-19 “Vaccines” Increase Your Risk of SEVEN Cancer Types
2 Landmark Studies tracked 8.7 MILLION people in Italy and South Korea — comparing vaccinated vs unvaccinated.
Breast, bladder, lung, prostate, thyroid, gastric, and colorectal cancers ALL surged after vaccination. https://t.co/M03HJoUZOu pic.twitter.com/txQF0HRKIY
— Nicolas Hulscher, MPH (@NicHulscher) October 6, 2025
Peter A McCullough, MD, PhD, whose tweet supporting the claim received more than half a million views, and Dr Aseem Malhotra, a cardiologist and activist, both reinforced these claims.
BREAKING: Large Population Study Finds COVID-19 Vaccines Increase Risk of 6 Major Cancers
South Korea study of 8.4 million adults finds higher risks of overall, lung, prostate, thyroid, gastric, colorectal, and breast cancers — across both mRNA and viral-vector platforms.… pic.twitter.com/2PLFn6u9HQ
— Peter A. McCullough, MD, MPH® (@P_McCulloughMD) September 28, 2025
Malhotra stated that the South Korean study was “important and concerning”, thus adding undue “medical” weight to the unfounded allegations.
I’m afraid one of Britain’s most eminent oncologists Professor Angus Dalgleish may well be right on the covid ‘vaccines’ fuelling cancer. This study published in a very respected high impact journal is significant and concerning https://t.co/oCc3zmovv1 pic.twitter.com/4fxSQtu7rQ
— Dr Aseem Malhotra (@DrAseemMalhotra) September 28, 2025
Additionally, the Children’s Health Defense organisation, which campaigns against childhood health epidemics, adopted this misleading narrative and published a report titled All COVID Vaccines Increase Cancer Risk, New Study Concludes.
What did they get wrong?
Al Jazeera’s fact-checking agency, Sanad, examined the original study and discovered that the promoters of this misinformation were omitting a key phrase from the excerpts they cited: “epidemiological association without causal relationship”.
In scientific terms, an “epidemiological association” indicates a statistical relationship or common pattern between two events, without implying that one causes the other.
To illustrate, if ice cream sales rise in the summer while drowning incidents also increase, there is an epidemiological correlation, but this does not mean that ice cream causes drowning; the common cause is warm weather causing people to eat ice creams and go swimming.
The manipulation occurs when this correlation is twisted into “definitive causality”, the trap influencers fell into. They ignored the scientific warnings and promoted the claim that vaccines “increase the risk”.
The true explanation likely lies in a phenomenon known as “surveillance bias”. People who were more inclined to receive the vaccine were often more diligent about medical check-ups and regular screenings, meaning cancer was diagnosed earlier – not caused by the vaccine.
What did the South Korean study actually say?
Contrary to the claims circulating, the Korean researchers emphasised the limitations of their conclusions and denied offering any evidence of causality.
In their conclusion, the study’s authors stated: “Given the limited availability of real-world data, our population-based cohort study in Seoul, South Korea suggested epidemiological associations between the cumulative incidence of cancers and COVID-19 vaccination, which varied by sex, age and vaccine type. However, further studies are warranted to elucidate potential causal relationships, including the underlying molecular mechanisms related to COVID-19 vaccine-induced hyperinflammation.”
This quote clearly shows that the study presented only “epidemiological associations” and called for further research to explore potential causal links. Therefore, any claim that vaccines “cause” cancer is a direct distortion of the facts.
Is there any evidence that COVID vaccines do cause cancer?
No. Beyond the controversy surrounding the South Korean study, global medical and scientific authorities have unequivocally affirmed the safety of the vaccines and have denied any link to cancer.
Experts from BMJ, the medical journal, have stated that there is no evidence supporting claims that mRNA vaccines are linked to cancer, noting that global epidemiological tracking data shows no surge in cancer cases following vaccine rollouts.
The Global Vaccine Data Network (GVDN) described the idea of a “cancer epidemic” caused by vaccines as a myth that contradicts biology and physics. They emphasised that there is no plausible biological mechanism through which mRNA vaccines could cause cancer, as these vaccines do not contain live viruses and do not enter the cell nucleus.
In a separate study, Fox Chase Cancer Center, the research institute, found that mRNA vaccines are safe, even for individuals undergoing active cancer treatment, with side effects comparable with those seen in the general population. The charity, Blood Cancer UK, also urged patients to continue receiving seasonal vaccinations, stressing that there is no large-scale, controlled study showing an increased cancer risk after vaccination.
Finally, the National Cancer Institute in the United States confirmed that “there is no evidence that COVID-19 vaccines cause cancer or lead to its recurrence or progression”. Thus, any assertion that vaccines “cause” cancer is a direct misrepresentation of scientific facts and global epidemiological data.
