Large Study Shows COVID Shots Increase Risk of Multiple Cancers

Hong Hin Kim, Min-Ho Kim, Myeong Geun Choi, Eun Mi Chun, September 2025

This large-scale population based study was done in Seoul, South Korea with data from 2021 through 2023 involving 8.4 million people.

Overall risk of cancer was 27% higher in vaccinated vs. unvaccinated (HR 1.27, 95% CI 1.21-1.33).

Lung cancer risk increased by 53% (HR 1.53, 95% CI 1.25-1.87).

Prostate cancer risk increased by 69% (HR 1.69, 95% CI 1.35-2.11).

Thyroid cancer risk increased by 35% (HR 1.35, 95% CI 1.21-1.52).

Stomach cancer risk increased by 34% (HR 1.34, 95% CI 1.13-1.58).

Colorectal cancer risk increased by 28% (HR 1.28, 95% CI 1.12-1.47).

Breast cancer risk increased by 20% (HR 1.20, 95% CI 1.07-1.34).

Vaccine Platform

cDNA vaccines (eg. AstraZenica) increased overall risk of cancer by 47% (HR 1.47, 95% CI 1.39-1.56).

mRNA vaccines (eg. Pfizer/Moderna) increased overall risk of cancer by 20% (HR 1.20, 95% CI 1.14-1.26).

Mixed schedules increased overall risk of cancer by 34% (HR 1.34, 95% CI 1.21-1.48).

Booster Dose Risk

Booster doses increased the risk of stomach cancer by 23% (HR 1.23, p=0.041).

Booster doses increased the risk of pancreatic cancer by 125% (HR 2.25, p<0.001).

Overall Trends

All demographic groups, including young adults, had a higher incidence of cancer. The mean age of individuals in this study was 44yo.

Men had a higher risk for stomach and lung cancers.

Women had a higher risk for thyroid and colorectal cancers.