Is the Polio vaccine linked with Cancer?
The polio vaccines developed by Jonas Salk and Albert Sabin in the mid-20th century were made with monkey cells. Years later, microbiologist Maurice Hilleman found a monkey virus in both vaccines—the 40th monkey virus to be discovered, which he called Simian Virus 40 (SV40). (Salk’s killed vaccine, which had been treated with formaldehyde, had very small amounts of the virus; Sabin’s live vaccine was heavily contaminated.) Worried about the potential effects the virus could have on humans, Hilleman injected it into hamsters, finding that nearly all of them developed massive cancerous tumors. But the initial panic this caused gave way in the face of future studies.
First, hamsters that ingested SV40 instead of being injected with it didn’t get cancer. Sabin’s live vaccine (which contained more SV40 than Salk’s) was given orally. Additional studies showed that children who were given Sabin’s vaccine did not develop antibodies to SV40; it simply passed through their digestive system, never causing infection.
That left only Salk’s vaccine, which contained very little SV40, but was given by injection. Studies performed eight years, fifteen years, and thirty years after SV40-contaminated vaccines had been given to children found that they had the same cancer incidence as unvaccinated groups. No credible evidence suggests that SV40 has ever caused cancer in humans.