Simian virus 40 (SV40) is used in the manufacturing process for mRNA vaccines.

We revised this check on Nov 7, 2026. See what changed and why ↓

The finding

What the evidence shows

McCullough moves between the SV40 virus and regulatory DNA sequences. MHRA explains that a short SV40-derived sequence in Pfizer's DNA template does not encode the viral large T antigen. It is not equivalent to using infectious SV40 or its cancer-causing gene to manufacture the vaccine. Residual DNA and assay-specific safety questions require their own evidence.

Read the supporting source · assets.publishing.service.gov.uk ↗

Quick answer & review status

Quick answer

Is it true that Simian virus 40 (SV40) is used in the manufacturing process for mRNA vaccines?

Partly. The claim stretches what the evidence shows. McCullough moves between the SV40 virus and regulatory DNA sequences. MHRA explains that a short SV40-derived sequence in Pfizer's DNA template does not encode the viral large T antigen. Dr. Peter McCullough said it (matched by voice) on Joe Rogan Experience #2576 - Dr. Peter McCullough, aired Nov 4, 2026, at 2:05:18. The supporting source is assets.publishing.service.gov.uk, linked below.

The context belongs here.

No separately verified on-air correction is recorded for this check. That is not a claim that nobody corrected it.

Attribution: Not independently confirmed in this record
Editorial context review: Not recorded; generated finding
Coverage: One selected claim from the episode

Revisions to this check

Nov 7, 2026

Previously: Simian virus 40 (SV40) is used in the manufacturing process for mRNA vaccines. [Distorted]: No simian virus 40 is used to make the mRNA vaccines. The DNA template Pfizer uses to make its mRNA contains a short, non-infectious stretch of genetic code copied from SV40, called a promoter-enhancer, and that template is broken down during manufacturing. Experts quoted by AAP FactCheck say this short sequence cannot produce virus. McCullough's own description of making mRNA from a DNA template in E. coli matches this, but calling it the virus overstates it. Evidence that whole SV40 virus or its cancer-linked T antigen gene is used in production would change this verdict.

Now: Simian virus 40 (SV40) is used in the manufacturing process for mRNA vaccines. [Distorted]: McCullough moves between the SV40 virus and regulatory DNA sequences. MHRA explains that a short SV40-derived sequence in Pfizer's DNA template does not encode the viral large T antigen. It is not equivalent to using infectious SV40 or its cancer-causing gene to manufacture the vaccine. Residual DNA and assay-specific safety questions require their own evidence.

Replace a secondary explanation with the regulator's specific distinction between viral sequences and the virus.

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