Fact Check: Did the CDC Admit to Giving a ‘Cancer Virus via the Polio Shot’?

It should come as no surprise to TWS Fact Check readers that much confusion and misinformation surrounds the subject of vaccines.

“CDC Admits 98 Million Americans Were Given Cancer Virus Via The Polio Shot,” one headline from ushealthmagz.com told readers last weekend. The article gained popularity on Facebook pages like “Cure For Life” and “Medical Marijuana a New Beginning,” with some readers suggesting that the “next time someone tells you a vaccine is mandatory tell them to kiss your ass both cheeks” and that “a friend who was a psychic healer … told me that the original polio shot had cancer in it. Most people thought he was crazy.”

“The CDC has admitted that between 1955–1963 over 98 million Americans received one or more doses of a polio shot,” the article claims, “which was contaminated with a cancer-causing virus called Simian vacuolating virus 40 (SV40).”

What’s the truth?

The CDC addresses this old rumor under the “common concerns” section of vaccine safety.

From 1955 to 1963, an estimated 10-30% of polio vaccines administered in the US were contaminated with simian virus 40 (SV40). The virus came from monkey kidney cell cultures used to make polio vaccines at that time. Most of the contamination was in the inactivated polio vaccine (IPV), but it was also found in oral polio vaccine (OPV). After the contamination was discovered, the U.S. government established testing requirements to verify that all new lots of polio vaccines were free of SV40.
Because of research done with SV40 in animal models, there has been some concern that the virus could cause cancer in humans. However, most studies looking at the relationship between SV40 and cancers are reassuring, finding no causal association between receipt of SV40-contaminated polio vaccine and development of cancer.


The Children’s Hospital of Philadelphia noted in 2016 that “findings do not support the hypothesis that SV40 virus contained in polio vaccines administered before 1963 cause cancer” and “studies do not show an increased risk of cancers in those who received polio vaccine between 1955 and 1963.”

The article from ushealthmagz.com alleges that the CDC deleted a web page containing information on this subject—and the organization’s supposed admission—however, the CDC told TWS Fact Check that its website has been updated and the information has moved to a new web page (previously cited). The old web page was last updated in 2016 and is now a dead link. The old web page also stated “the majority of scientific evidence suggests that SV40-contaminated vaccine did not cause cancer” noting too that “some research results are conflicting and more studies are needed.”

Which leads us to, as so often is the case with modern science caught up in a brief moment, a very unresolved ending. Ushealthmagz.com’s claim that SV40 is a “cancer virus” (or rather, a cancer-causing virus) is yet unproved. SV40 has been found in different types of cancer, but there is no consensus as to whether or not SV40 causes those cancers. Psychic healers aside, the Children’s Hospital in Philadelphia’s research notes that “studies do not show an increased risk of cancers in those who received polio vaccine between 1955 and 1963.”

If you have questions about this fact check, or would like to submit a request for another fact check, email Holmes Lybrand at [email protected] or the Weekly Standard at [email protected]. For details on TWS Fact Check, see our explainer here.

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