Is DNA hidden in vaccines causing cancer?

SV40 is a simian virus that is most commonly found in the kidneys of several kinds of monkeys. It can also sometimes infect humans and can potentially cause cancer via tumor (T) antigens. Unfortunately, early batches of the polio vaccine became contaminated with SV40, and the methods used to inactivate the poliovirus did not reliably inactivate SV40. Importantly, epidemiological studies have found no increased cancer risk in those who received these vaccines.

Since then, a promoter gene (a DNA sequence that starts RNA transcription) of SV40 has been found to promote a high level of gene expression for producing proteins and has been used in DNA vaccines. The sequence used is just the promoter gene and does not include any part of the DNA sequence that encodes for the T antigen of SV40. While promoters like the SV40 promoter are used in the manufacturing of mRNA vaccines, they are not considered an ingredient in the vaccines as the vast majority of it is removed during production.

Manufacturing vaccines for a small batch for a trial is a very different process than manufacturing of thousands of doses at a time. Process 1 is the small batch process, while process 2 is the scaled-up version. Although the processes are different, they are both held to the same safety and quality standards.

Original claims that DNA plasmids were found in mRNA vaccines at a higher proportion of mRNA to DNA than is allowed by FDA guidelines stem from a previous preprint paper acknowledging that one limitation of the study is the “unknown provenance of the vaccine vials under study.” They also note that the vaccines arrived without proper cold chain processes and were all expired. They follow up that paper with this preprint, where the authors obtained and tested “24 unopened expired vials” and “three vials of in-date remnants”. As mRNA degrades much faster than DNA, especially when held in suboptimal conditions, any proportion of trace amounts of DNA used in manufacturing would be amplified in expired vials, as these were,  or ones not held in optimal conditions.

Find more posts from Voices for Vaccines on SV40.