Study: Residual DNA in Pfizer and Moderna Vials

Simian Practicalist
Sep 23
2 min read

A study by D.J. Speicher, J. Rose and K. McKernan titled “Quantification of residual plasmid DNA and SV40 promoter-enhancer sequences in Pfizer/BioNTech and Moderna modRNA COVID-19 vaccines from Ontario, Canada” posted on 6 September 2025 has found more residual DNA rubbish in Pfizer and Moderna “vaccine” vials.

The paper is 21 pages in total, with the main text at about 17 pages. Here is a little background:

In 2023, McKernan et al. subjected COVID-19 modRNA vaccine vials to next-generation RNA sequencing and, found unexpected evidence of DNA derived from the template plasmids used during manufacturing. This showed that both Pfizer and Moderna vaccines contained high copy plasmid components with different residual DNA sequences. Additionally, McKernan et al. found that all Pfizer vaccines contained SV40 promoter-enhancer-ori and SV40 polyA signal sequences being utilized as the promoter for the Kan/Neo selectable marker. These residual DNA components were absent from the required disclosures in EMA regulatory documents. Based on this information, McKernan et al. developed a qPCR method to quantify the level of residual plasmid DNA in the vaccine vials targeting multiple loci in the Moderna and Pfizer plasmids.

The researchers examined 32 vials in total from 16 lots—10 vials (6 lots) of Pfizer and 22 vials (10 lots) of Moderna—using the abovementioned qPCR method and fluorometry. The lot approval dates range from June 2021 to September 2023. Most were sealed but expired.

The amount of spike, ori and SV40 promoter-enhancer-ori DNA was analyzed. The short version is that the researchers found “the presence of billions to hundreds of billions of DNA molecules per dose in the modRNA COVID-19 products tested”.

Using fluorometry coupled with RNase A digestion, all products tested exceeded the guidelines for residual DNA set by the FDA and WHO of 10 ng/dose by 36–627-fold. qPCR testing showed that all Moderna vials were within the regulatory limit and that 3 Pfizer vials exceeded the regulatory limit for the SV40 promoter-enhancer-ori and showed much greater intra- and inter-lot variability.

What is interesting is that the authors lined up the reported adverse events as recorded in VAERS to their corresponding lots and their DNA content. Figure 2 is reproduced below. Note the logarithmic scale on the top graph for total pg DNA per dose.

Figure 2: Comparison of residual DNA content of spike (red) ori (blue), SV40 promoter-enhancer-ori (green) as measured by qPCR, and the total number of adverse events (orange) reported to VAERS. The historic (10 pg/dose) and current (10 ng/dose) FDA and WHO regulatory guideline for residual DNA is shown by a red dotted line.

Even just visually, one can see that adverse events are associated with the presence of SV40 and higher levels of ori.

Of no less importance is the ridiculous variation between lots, evidence of a highly inconsistent production and quality control process. This has been pointed out by Dr Yeadon back in 2022 if not earlier.

Since consistency is a must in pharmaceutical products, such a vaccine being released suggests gross negligence at best.

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