What was claimed
The Pfizer Covid-19 vaccines contain “cancer-causing SV40”, a virus which was used in experiments to cause mice to develop tumours.
Our verdict
This is not correct. The vaccine does not contain the SV40 virus, which has been used to induce cancer in laboratory animals. It uses a fragment of the SV40 DNA sequence, which does not cause cancer or produce an infectious virus.
The Pfizer Covid-19 vaccines do not contain a “cancer-causing” infectious monkey virus, contrary to a video circulating online.
In a video on Facebook, which has been shared 10,000 times, and on Instagram where it has over 21,000 likes , Professor Angus Dalgleish, an oncologist, says: “The Pfizers [sic] are all full of SV40. SV40 was what in my day we put into mice to make them grow tumours so we could pour chemotherapy into them to see if it worked for the tumours.”
A more direct claim is made in the headline added to the video, which says: “Professor Angus Dalglesh [sic]: Big Pharma is “evil” for putting the cancer-causing SV40 into their jabs.”
However, claims that the Pfizer vaccine contains “cancer-causing SV40” are not correct. Infectious SV40 virus—which stands for Simian Virus 40, a DNA virus present in species of monkeys—is not present in the Pfizer vaccine.
The SV40 virus can induce cancer in laboratory animals. It was investigated as a possible cause of cancer in humans by a group of scientists in 2012. On their assessment of the evidence, SV40 was ‘not classifiable as to its carcinogenicity to humans’.
However, the virus itself simply isn’t present in the Pfizer vaccine. Instead, the vaccine contains a small, inactive piece of DNA related to SV40, known as an “SV40 enhancer sequence”.
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This sequence, which is used in the vaccine’s manufacturing process, does not cause cancer, or cause SV40 infections, according to the Medicines and Healthcare products Regulatory Agency (MHRA). It said in response to an FOI request: “The presence of the SV40 promoter enhancer sequence is not the same as the presence of the whole virus itself. The SV40 promoter enhancer sequence was found to be a residual DNA fragment in Pfizer-BioNTech COVID-19 vaccine.
“The fragment is inactive, has no functional role, and was measured to be consistently below the limit required by regulators.”
A Pfizer fact sheet says that the vaccine is made by using plasmid DNA as a starting material, which utilises non-infectious fractions of a SV40 sequence.
It also says that the DNA starting material does not contain oncogenes, which are genes that may have the potential to cause cancer.
Professor Deborah Fuller, a microbiologist at the University of Washington, told fact checkers at AAP that the starting material contains an ‘enhancer or promoter sequence’—which is a copy of a short non-infectious sequence of SV40 DNA—and said it is “not possible for this short sequence to produce infectious virus”.
We have attempted to contact Professor Dalgleish about the comments he made in the video and will update this article if we receive a response.
He was cited by the cardiologist Dr Aseem Malhotra at the Reform conference as the source for a claim that the Covid-19 vaccine had led to cancers within the Royal Family, There is no evidence for that claim, which we fact checked at the time.
We have fact checked the false and misleading claims that the Covid-19 vaccines cause cancer many times before.
This article is part of our work fact checking potentially false pictures, videos and stories on Facebook. You can read more about this—and find out how to report Facebook content—here. For the purposes of that scheme, we’ve rated this claim as false because the Pfizer vaccine doesn’t contain the SV40 monkey virus, which has been used to induce cancer in laboratory animals. It does use a fragment of SV40 DNA sequence, but this does not cause cancer and cannot produce an infectious virus.
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