Korean Disease Agency Rejects Causal Link Between Vaccines and Cancer (Yonhap)
SEOUL, Oct. 14 (Korea Bizwire) — South Korea’s Disease Control and Prevention Agency (KDCA) pushed back on Monday against a recent study by domestic medical researchers suggesting that COVID-19 vaccines could increase the risk of cancer, saying the findings do not establish a causal link.
“The mechanisms behind cancer development take years to identify,” a KDCA spokesperson said during a regular briefing. “It’s difficult to conclude that vaccination caused cancer based on a one-year observation period.” The agency added that “the study has been widely criticized within the academic community for its methodological limitations.”
The KDCA reaffirmed that the protective benefits of COVID-19 vaccination remain well-established, noting that severe illness and death prevention effects have been documented globally over several years. Reported adverse reactions in Korea also declined to about five cases per 100,000 vaccinations during the 2024–2025 inoculation period, most of which were minor, it said.
The agency urged high-risk groups, including older adults, to continue receiving seasonal boosters. “Starting October 15, simultaneous vaccination for COVID-19 and influenza will be available for citizens aged 75 and above,” said KDCA spokesperson Go Jae-young, emphasizing that combined inoculation “does not increase the incidence of side effects.”
The controversy stems from a study led by Prof. Chun Eun-mi of Ewha Womans University Mokdong Hospital, published last month in the international journal Biomarker Research. Using data from the National Health Insurance Service covering about 8.4 million Koreans vaccinated between 2021 and 2023, the team analyzed correlations between vaccination history and cancer diagnoses across age, gender, and vaccine type.
The study reported higher one-year risks for certain cancers among vaccinated individuals, including a 69% increase in prostate cancer and a 53% rise in lung cancer, compared with unvaccinated groups.
However, experts cautioned against overinterpreting the results, noting flaws in comparing vaccinated and unvaccinated populations, limited observation periods, and confounding factors such as health behavior differences.
Even the authors acknowledged the need for further investigation, writing that while their findings “suggest an association between vaccination and cancer incidence,” additional long-term research is required to determine causality.
Lina Jang (linajang@koreabizwire.com)
