From the article;
As the world races to fast-track a COVID-19 vaccine, bringing an experimental shot to market faster than has ever occurred in history, the potential risks of medical procedures like vaccination must be carefully weighed. Unintended harms can and do occur following vaccination, and the inactivated and live polio vaccines are prime examples.
From 1955 to 1963, hundreds of millions of people worldwide — in North and South America, Canada, Europe, Asia and Africa — received polio vaccines that may have been contaminated with simian virus 40 (SV40), a monkey virus.1 The video above is a decade old, but it succinctly summarizes the serious consequences that can occur from vaccine contamination — consequences that may not be realized until many years later.
In the video, Dr. John Bergsagel, then a pediatric oncologist, looks at laboratory slides of tumors taken from children who died of extremely rare brain cancers. When SV40-like DNA sequences were detected in them, he said, “I almost fell out of my chair. I was very surprised.”
The finding, published in The New England Journal of Medicine in 1992, revealed that half the choroid plexus tumors and most of the ependymomas studied contained a segment of T-antigen gene related to SV40.
“These results suggest that SV40 or a closely related virus may have an etiologic role in the development of these neoplasms during childhood,” they wrote2 — and this was only the beginning of findings linking monkey virus-contaminated polio vaccines to cancer.