South Korean Study Misused to Spread False Vaccine Claims

A wave of misinformation recently claimed a South Korean study “proved” that COVID-19 vaccines increase cancer risk. The posts cited alarming statistics — including supposed 27% and 69% increases — and were widely shared by doctors, influencers, and anti-vaccine platforms.

In reality, the peer-reviewed paper, published in Biomarker Research, did not show any causal relationship between vaccination and cancer. The study found only epidemiological associations — statistical patterns between vaccinated individuals and later diagnoses — which are not evidence of cause and effect.

The authors explicitly warned that their findings show “no causal relationship” and urged caution in interpretation. Experts attribute the observed trend to “surveillance bias”: people who get vaccinated tend to have more medical checkups, leading to earlier detection, not higher incidence.

The World Health Organization confirmed the study was observational and cannot establish causality. Global data from institutions including BMJ, the Global Vaccine Data Network, and the U.S. National Cancer Institute continue to show no increase in cancer rates after vaccination.