Recent revelations about the presence of DNA fragments in the Pfizer and Moderna COVID-19 vaccines have stirred concerns and prompted questions about the FDA's role in monitoring vaccine safety.
The FDA has long been aware of the potential risks associated with residual DNA in vaccines, acknowledging the possibility that these DNA fragments could integrate into a patient's own DNA, potentially leading to issues such as cancer.
Traditionally, FDA and WHO guidelines have set a limit of 10 ng (one billionth of a gram) of residual DNA per dose for traditional vaccines. However, these guidelines may not be directly applicable to mRNA vaccines like Pfizer and Moderna's, as their lipid nanoparticles can efficiently deliver mRNA into cells. A recent study by Speicher et al analyzed batches of mRNA vaccines in Canada, finding billions to hundreds of billions of DNA molecules per dose, exceeding the established guidelines.
Notably, the study observed a correlation between the level of DNA fragments in the Pfizer vaccine and the occurrence of serious adverse events. While some experts argue that the risk of genome integration in humans is low, a Nature publication suggests around 7% of cells can integrate when mixed with a transfection solution containing linear DNA pieces.
The FDA, however, maintains that the minute amounts of residual DNA in the COVID vaccines do not pose a problem and insists on the safety and efficacy of mRNA vaccines. Despite this assurance, the FDA has not provided the scientific evidence supporting its claims. Additionally, product labels for the vaccines reveal that genotoxicity and carcinogenicity tests were not conducted before their use.
David Wiseman, a research bioscientist involved in medical product development, questions the FDA's stance, especially in light of the CDC's analysis showing a potential signal for some cancers. The FDA has not confirmed if it found DNA levels exceeding acceptable limits or if further investigations are underway.
Furthermore, concerns arise regarding Pfizer's manufacturing oversight. It is revealed that the vaccine used in clinical trials (PROCESS 1) differed from the one administered to the public (PROCESS 2), introducing plasmid DNA impurities that could alter the vaccine's safety profile. The FDA claims ongoing testing, but accessing results is challenging, and Pfizer's commitment to comparative testing seems unfulfilled.
Experts like Kevin McKernan, who discovered the DNA fragments, suggest that Pfizer might not have incentives to conduct comparative testing, speculating that increased adverse events with commercial batches could have been concealed. The overall situation raises questions about regulatory oversight and transparency in ensuring the safety of COVID-19 vaccines.
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