Did a South Korean study really claim that COVID-19 vaccines cause 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"

A South Korean population-based cohort study used national health insurance data from 2021–2023 covering over 8.4 million people to examine one-year cancer diagnoses after COVID-19 vaccination. The analysis reported a statistical association in which vaccinated individuals were more likely to receive diagnoses of certain cancer types within one year. Those correlations were widely amplified on social media and reframed by influential accounts as proof of causal risk, citing figures such as a 27% overall increase and larger percentages for lung and prostate cancers. Statistical correlation does not equal causation; confounding, detection bias, multiple comparisons, and chance could explain the findings. Professional credentials were leveraged to amplify misleading claims, contributing to public alarm and the spread of misinformation that requires careful scientific review and further study.

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