Communication on Methodological Considerations Regarding the Quantification of DNA Impurities in the COVID-19 mRNA Vaccine Comirnaty^®. Methods Protocols 7, 41 (May 2024)

The purpose of this communication is to clarify criticisms that have arisen in the context of our publication "Methodological Considerations Regarding the Quantification of DNA Impurities in the COVID-19 mRNA Vaccine Comirnaty®" (Methods and Protocols 2024, 7, 41, May 2024 [1]). After an exchange of opinions, a comment was submitted within a Comment and Reply Procedure started by Methods and Protocols by Kaiser and Marschalek [2], in which they assailed our publication. But after reading our reply which we submitted by 24 September 2024, Kaiser and Marschalek decided to submit the data contained in their comment in parallel together with further authors as a regular article to another journal, titled "Quantification of objective concentrations of DNA impurities in mRNA vaccines" (Kaiser et al 2025 [3]), of which an earlier version has been published as a preprint already in November 2024 (Kaiser et al 2024 [4]). This publication and preprint attempted to refute our findings obviously aiming to be published without our resoponse and undermining the Comment and Reply Procedure. However, it does not succeed in doing so with the necessary persuasiveness. First of all, it is particularly important that Kaiser and Marschalek [2] and Kaiser et al [3, 4] have confirmed that our results are reproducible when the quantification is carried out using the Qubit® technology in accordance with the manufacturer's instructions, which is exactly what we did. However, it is then claimed by Kaiser and Maschalek [2] as well as by Kaiser et al [3, 4] that the magnitude of the DNA impurities we have shown would be an effect of high amounts of RNA present in the samples. As a proof they quantified a defined concentration of DNA in the presence of very high concentrations of RNA with the Qubit® methodology. However, even the presence of 250 ng/µL RNA resulted only in a comparatively small increase in the DNA value of 0.655 ng/µL and this is far from explaining the DNA concentrations of 12 to 17.8 ng/µL that we have measured in several batches of Comirnaty®. Further, Kaiser and Marschalek [2] and Kaiser et al [3, 4] mentioned that experiments with DNA extracted from the vaccine would show that the very low legal limits for DNA in Comirnaty® are met. However, the authors of this critique have failed to demonstrate that the extractions they performed are indeed quantitative, i.e. reflect the actual DNA contamination. But, based on the related published literature, this must be denied. With this in mind, we can finally confirm that both our methodology and our data, as published in our above-mentioned article [1], imply that DNA impurities as measured with Qubit® by us in Comirnaty® are reliable according to the manufacturer's premises for this DNA quantification technology. In this sense, the DNA values presented by Kaiser and Marschalek [2] and Kaiser et al. [3, 4] after extraction procedures are obviously artificial effects of the extractions performed and therefore do not represent the true DNA contamination of the concerned Comirnaty® batches. Finally, our data for DNA contaminations in Comirnaty have been confirmed in December 2024 explicitly by research utilizing different Methods which has been conducted in a Labortory of the US Food and Drug Administration FDA [5]. However, this publication has been ignored by Kaiser et al. in their own publication of March 2025 [3] which appeard almost 3 months later and thus should have cited and discussed the particular findings which are confirming our data.