evidence: As with many medical products, the mRNA COVID-19 vaccines may contain trace amounts of residual DNA from the manufacturing process. It is not considered adulteration, and the Food and Drug Administration is not "required" to pull the vaccines from the market, contrary to viral claims online. [...] Recently, some people have claimed that the residual DNA in some mRNA COVID-19 vaccine vials is above the regulatory limit — and that some of the short sequences could be harmful and cause cancer if they integrated into a person’s genome. But as we have written, there isn’t reliable evidence that the residual DNA in the vaccines is too high, nor is there evidence that the DNA integrates, much less that it causes cancer or any other health problem. [...] Health Canada told us in an email that the "SV40 promoter enhancer sequence was found to be a residual DNA fragment in Pfizer-BioNTech COVID-19 vaccine," but that the "fragment is inactive, has no functional role, and was measured to be consistently below the limit required by Health Canada and other international regulators." It iterated that this was not a safety concern.