Contested South Korean Study Links COVID Vaccines, Cancer

A South Korean study published in Biomarker Research analyzed health records of more than 8.4 million adults from 2021–2023 and reported associations between receipt of at least one COVID‑19 vaccine dose and higher risks of six cancers—thyroid (~35%), gastric (~34%), prostate (~68%), lung (~53%), breast (~20%) and colorectal (~28%)—with the greatest apparent risk in people over 65. The analysis included mRNA vaccines (Pfizer, Moderna) and other vaccine types and did not propose a biological mechanism or establish causation. The study has been widely criticized by oncologists and scientists as methodologically limited, potentially conflating correlation with causation, and described by some outlets as “scientifically inaccurate” or “superficially alarming.” These contentious findings sit alongside extensive evidence supporting COVID‑19 vaccine safety and public‑health benefits, including studies showing maternal vaccination is safe in pregnancy and reduces infant hospitalizations, and do not overturn the broader vaccine‑safety consensus.